Alien Ideas

Christianity and the Search for Extraterrestrial Life


We tend to consider speculation about extraterrestrials to be a recent phenomenon, a task forced on us by the scientific knowledge we’ve gained during the last century. It’s rather surprising, perhaps, to find out that the debate about whether there is extraterrestrial life stretches back just shy of two and a half millennia.

Given the antiquity of the question, we might be even more surprised to find that the Catholic Church has never issued any formal pronouncement, one way or the other, about the existence of extraterrestrial life.

Yet unofficial pronouncements have recently come from respected sources connected to (but not speaking for) the Vatican. Rev. George Coyne, director of the Vatican Astronomic Observatory, considers the possibility of extraterrestrials an “exciting prospect, which must be treated with caution…. The universe is so large that it would be folly to say that we are the exception.” Rev. Christopher Corbally, S.J., another astronomer at the Vatican Observatory, believes that if we discover extraterrestrials, it will entail an expansion of our theology, for “while Christ is the First and the Last Word (the Alpha and the Omega) spoken to humanity, he is not necessarily the only word spoken to the whole universe.”

Theologians have weighed in as well. Thomas O’Meara, O.P., professor of theology at Notre Dame, argues, “The history of sin and salvation recorded in the two testaments of the Bible is not a history of the universe; it is a particular religious history on one planet.” For O’Meara, “the central importance of Jesus for us does not necessarily imply anything about other races on other planets…. Believers must be prepared for a galactic horizon, even for further Incarnation.”

It would seem, then, that for Catholics the question of whether to believe in extraterrestrials is wide open. Tempting as such speculation is, however, a closer look at the history of the debate in relationship to Christianity might take some of the wind out of our speculative sails.

Atomism and Aliens

To begin with, Christians inclined toward believing in the existence of extraterrestrials should be aware that such belief makes for strange bedfellows. Historically, the idea of aliens arose more than 2,000 years ago among the ancient atomists (Democritus, but especially Epicurus and Lucretius) as part of an overall philosophical argument, rooted not in evidence but in the desire to rid the world of religion.

According to Epicurus and Lucretius, belief that the gods interfere in human affairs was the root of all evil, causing human beings to engage in all manner of vile and foolish activities from war to child sacrifice. In Lucretius’s famous words (which 17 centuries later were to become a favorite taunt of the anti-Christian elements of the Enlightenment), “Tantum religio potuit suadere malorum” (Only religion was able to persuade men of [such] evil things).

The Epicurean solution? A rather modern-sounding one: Eliminate religion by embracing a materialist view of the universe. The atomists got rid of the need for a divine creator of nature by asserting that everything in the universe came into being as a result of the chance jostling of brute matter (a.k.a., atoms). Because the number of atoms in a limitless universe is infinite, the random motion of the atoms must have produced a “plurality of worlds.” As Lucretius declared in On the Nature of the Universe, if “the purposeless congregation and coalescence of atoms” brought about all living things in our world–plants, people, and everything in between–then certainly “in other regions there are other earths and various tribes of men and breeds of beasts.”

Since the first speculation about the existence of extraterrestrials bubbled up from the materialist belief that chance could spin forth a variety of reasoning creatures with ease, Christians ought to be a bit more careful about heaving themselves into the same theoretical hammock, so to speak.

The Advent of Christianity

To further sharpen the point, there were both cosmological and theological reasons why early Christians either did not believe in extraterrestials or refused to speculate about them. The early Christians held to a geocentric universe: The earth was the only location possible for intelligent embodied beings. As patristics scholar Rev. Joseph Lienhard points out, there were no extraterrestrials in either the Epicurean or modern sense, because in the world of the early Christians, “anything ‘extra terram’ (that is, apart from earth and water) had to live in the air–hence, they would be spirits of some sort…. In no case I know of did a Father of the Church postulate corporeal beings living on some other planet.” According to Father Lienhard, the closest thing we find among the early Christians is the belief of some (rooted in neo-Platonism) that “the seven planets or wanderers (the sun, moon, and five visible planets) were indwelt by rational beings or minds” because their circular motion “had to have a rational origin.”

Such rude cosmology may strike us as irrelevant, but the early Christians also had theological reasons for their position. First, in direct contrast to the Epicureans, Genesis makes it clear that God (not chance) created the universe and, consequently, that human beings were intentionally (not accidentally) created by God. Second, according to Scripture, the universe is already quite well populated with intelligent extraterrestrials; they’re called angels. But most important of all, the incarnation of Christ was the union of God’s divinity with our humanity. Human beings were thereby placed at the center of the cosmic drama, which made no room for questions about the redemption of other intelligent beings (even angels).

For all these reasons, we find no evidence of speculation about extraterrestrials among the early Christians. Not only did such speculation run directly against the central doctrinal claims of Christianity, but it also smacked of Epicureanism (which entailed, among other things, the denial of the immortal, immaterial soul, heaven, and hell). Small wonder the early Christians tossed the Epicurean package, extraterrestrials and all, into the abyss of doctrinal errors.

And there it stayed for nearly a thousand years.

The Rise of the Modern Extraterrestrial Debate

Three things caused the debate about extraterrestrials to resurface in the West: the theological anti-Aristotelianism of the late 13th century, the rediscovery of ancient atomism in the 15th century, and the invention of the telescope in the early 17th century.

Beginning about 1100 a.d., text after text of the great Greek philosopher Aristotle reached the West, and Christians were suddenly confronted with a unified, well-constructed account of the universe, an account written by a pagan. Aristotle denied that there could be a plurality of worlds. Of course, if there could not be a plurality of worlds, then the question of extraterrestrials was moot.

There were three reactions to Aristotle’s purely natural, non-Christian philosophical account: vehement rejection (the radical Augustinians), careful embrace (St. Thomas), and passionate embrace (the radical Aristotelians).

Around 1265 a conflict between the two radical wings began to heat up, resulting in the famous (or, for Thomists, infamous) 219 Propositions in 1277, issued by the bishop of Paris, Etienne Tempier. Proposition 27 condemns all who hold the Aristotelian position “that the first cause cannot make more than one world.”

It should be stressed that the aim of this condemnation was not to affirm a plurality of worlds but to affirm God’s omnipotence against any account of nature that seemed to restrict God’s powers. Aristotle’s insistence that there could only be one world accorded nicely with the Genesis account of creation, but it appeared to the radical Augustinians to make God the servant of natural necessity rather than its master. The remedy, so Bishop Tempier and his followers thought, was to assert that the first cause could indeed create a plurality of worlds (even if we know, by revelation, that He happened to make only one).

But the condemnation had an unforeseen effect. No sooner had the ink soaked into the vellum than speculation about a plurality of worlds began in earnest. By the beginning of the 15th century, that speculation had led some Christian thinkers to affirm the existence of extraterrestrial life. In his On Learned Ignorance (1440), Nicholas of Cusa argued that “life, as it exists here on earth in the form of men, animals and plants, is to be found, let us suppose, in a higher form in the solar and stellar region.” Cusa then began to churn out a zoology:

It may be conjectured that in the area of the sun there exist solar beings, bright and enlightened intellectual denizens, and by nature more spiritual than such as may inhabit the moon—who are possibly lunatics—whilst those on earth [i.e., human beings] are more gross and material. [Quoted in Steven Dick, Plurality of Worlds: The Origins of the Extraterrestrial Life Debate from Democritus to Kanzt]

So it was that Christian speculation about lunatics and solarians moved from the lunatic fringe closer to the acceptable center. But exactly what is such let-us-supposing and conjecturing based on? Evidence? Revelation? Reason? No. In fact, it issued from an unhappy union of sloppy logic and untethered imagination. To affirm God’s omnipotence (by condemning the proposition that “the first cause cannot make more than one world”) does not entail that God indeed has created more than one world (and peopled it with aliens). As for footloose imagination, the embarrassing claim about solarians and lunatics speaks for itself.

Dovetailing neatly with this new Christian affirmation of the plurality of worlds (and even the possibility of extraterrestrial life), we have the rediscovery in the 15th century of the long-buried texts of Democritus, Epicurus, and Lucretius. During the next two centuries, the words of these ancient atomists spread all over Europe, becoming the foundation of the modern scientific revolution in the 17th and 18th centuries.

As we might expect, the atomists’ belief in extraterrestrials blossomed anew with the advance of the materialistic view of modern science. But in contrast to the ancient antagonism between such materialism and religion, modern atomism met with Christian theologians moonstruck by the possibility of lunatics. The Epicurean-Lucretian cosmology, designed to eliminate religion, was now welcomed as the bearer of galactic good news.

We’ll return to this irony below. Our analysis would be incomplete, however, if it did not include the visible support that the plurality-of-worlds theory seemed to receive with the invention of the telescope. When the new “spyglass” (as Galileo called it) was trained on the heavens in the early 17th century, the heavens were found to be far deeper and far, far more populated with stars than anyone could ever have imagined. Were these not the suns illuminating the infinite worlds promised by Epicurus and Lucretius?

When coupled with the earlier arguments of Copernicus–that the earth was not (as Aristotle had argued) the center of the universe–this open expanse of space filled with countless stars seemed to shatter any notion that our little sun and our little world were anything other than a drop in the cosmic bucket. For many Christians, the expanded cosmology seemed to demand an expanded theology.

The Era of Speculation (and Secularization)

From approximately 1600 to 1900 there was first a trickle, then a flood of scientific-philosophical-theological speculation on the nature of extraterrestrial life.

From this period, we can cull a veritable bestiary of extraterrestrials that were supposed to inhabit every known planet in our solar system, as well as the sun and moon and, beyond that, every star, planet, and comet in the universe.

Such speculation often came from the best scientists of the day. Sir William Herschel (1730-1822), the astronomer who discovered Uranus (1781), claimed that he saw near-certain evidence of forests, circular buildings, canals, roads, and pyramids on the moon—all, of course, signs of lunarians. He was equally certain that the known planets of our solar system were all peopled and insisted the sun was “a most magnificent habitable globe” filled with solarians “whose organs are adapted to the peculiar circumstances of that vast globe.” Sir John Herschel (1792-1871), William’s son, inherited both his father’s science and his fantasies; he argued that since the front side of the moon was apparently dead, lunarians must live on the dark side.

Johann Bode (1747-1826), a director of the Berlin Observatory and famous for Bode’s Law, asked of these same solarians, “Who would doubt their existence?” The reason for such certainty was quasi-theological. “The most wise author of the world assigns an insect lodging on a grain of sand and will certainly not permit…the great ball of the sun to be empty of creatures and still less of rational inhabitants who are ready gratefully to praise the author of life.” The same reasoning led him to affirm the existence of extraterrestrials on the moon, Mercury, and Venus.

We find, throughout this period, similar speculations approved by equally eminent scientists: Sir William Rowan Hamilton (1805-1856), Sir David Brewster (1781-1868), François Arago (1786-1853), J. Norman Lockyer (1836-1920), Jean Liagre (1815-1892), Jules Janssen (1824-1907), William Pickering (1858-1938)–and the list goes on well into the 20th century, a Who’s Who of the leading astronomers. As François Plisson, a French physician and coolheaded critic of extraterrestrial mania, wrote in 1847, “Almost all the astronomers of our day, and the most eminent among them, freely adopt the opinions that not long ago were viewed as being able to spring only from the mind of a madman.”

If belief in solarians, lunarians, jupiterians, venusians, mercurians, and martians seems madness now, during the 18th and 19th centuries it was taken to be the only rational, scientifically grounded view. Small wonder, then, that theologians–both Christian and deist–felt not only inspired but obliged to incorporate extraterrestrials into their systems.

Looking first at the Christian attempts, one notices immediately that the doctrine of the Incarnation underwent a transformation as well-intentioned Christians rushed to keep up with the latest menagerie of extraterrestrials.

To cite a few examples: John Wilkins, an Anglican theologian who would go on to become a bishop, penned a popular account of extraterrestrials called Discovery of a World in the Moone. Wilkins insisted that the existence of extraterrestrials would not contradict Christianity. The absence in Scripture of any mention of other worlds or extraterrestrials did not preclude the possibility of their existence because “’tis besides the scope of the Holy Ghost either in the new Testament or in the old, to reveale any thing unto us concerning the secrets of Philosophy,” and further, an inhabited “Moone” was an expression of God’s creative power, unduly restricted by believers, for too long, only to the earth.

A more famous and far more influential work was the quasi-Christian Bernard le Bovier de Fontenelle’s Conversations on the Plurality of Worlds (1686), which asserted that the existence of creatures on other planets would not upset Christianity because such creatures would not be descendants of Adam and therefore would not be subject to the Incarnation.

A bit later, and pushing things a bit further, Traité de l’Infini Créé was published in 1769, allegedly by Abbé Malebranche but actually by Abbé Jean Terrasson. In it, Terrasson argued, against Fontenelle, that the Incarnation was not peculiar to our planet. If “it is asked…if the eternal Word can unite himself hypostatically to a number of men [i.e., different rational creatures on multiple planets]; one responds without hesitation—yes. The men would all be men-God [hommes-Dieu], men in the plural, God in the singular, because these men-God would in effect be several in number as to human nature, but they would be only one in respect to divine nature.” Indeed, even where there was no Fall, Christ would embody Himself as a member of the race, for they deserved this honor even more than those who had fallen.

Other attempts to reconcile Christian revelation with extraterrestrials abound. William Hay (1695-1755) argued for multiple modes of salvation entailing multiple modes of Christ’s incarnation; James Beattie (1735-1803) asserted that Christ’s incarnation, death, and resurrection served as an inspiring example for all extraterrestrials; and Beilby Porteus (1731-1808) maintained that the Incarnation actually extends to all extraterrestrials.

By the beginning of the 19th century, belief in the plurality of worlds was so well accepted, especially among Protestants, that it was now incorporated as an essential element of evangelical orthodoxy. Some proponents, like Thomas Chalmers (1780-1847), were fairly cautious. Chalmers would say only that “for anything we can know by reason, the plan of redemption may have its influences and its bearings on those creatures of God who people other regions.”

But as we have seen, others showed less restraint. To such speculations, we should add those of the influential visionary Baron Emanuel Swedenborg (1688-1772), who claimed to have conversations with the angels of each of the planets of our solar system and reported that the lunarians speak very loudly “from the abdomen” because “the Moon is not surrounded with an atmosphere of the same kind as that of other earths.”

Ellen Harmon (1827-1915), prophetess and foundress of the Seventh-Day Adventists, reported after one of her visions that “the inhabitants [of Jupiter] are a tall, majestic people, so unlike the inhabitants of earth. Sin has never entered here.” The Mormons were another sect inspired by astronomical speculation; they also believed in a universe populated by a plurality of gods, angels, and extraterrestrials.

The Infinite Machine

Of course, Christians weren’t the only ones busy with theological speculation about extraterrestrials. The 18th century was a time of transition for the West, from a Christianized culture to a secularized culture. Deism, standing midway between Christianity and atheism, was the religion of transition.

To be more exact, deism was the religion of the Newtonians. At the end of the 17th century, Newton had used the materialist atomism, ultimately rooted in the thought of Epicurus and Lucretius, as a foundation for his geometrical account of nature. As a result, the closest Newton could come to Christianity was deism, in which a distant god created the atoms and gave them an initial shove. The Incarnation was simply jettisoned as cosmologically incompatible and therefore irrelevant.

Deist poet laureate Alexander Pope composed “The Universal Prayer,” which praised the deist god as the creator of multiple worlds and was intended by Pope to replace the all-too-provincial Lord’s Prayer. The works of the archdeist Voltaire, who called himself the new Lucretius, were shot through with multiple worlds peopled by extraterrestrials. On America’s own shores, Benjamin Franklin included such cosmic pluralism in his personal articles of belief, even claiming that the plurality of extraterrestrials included a plurality of gods to watch over each of the suns.

Perhaps more clearly than anyone else of the time, the deist Thomas Paine realized that the existence of a multitude of worlds (and, thus, of extraterrestrials) was entirely incompatible with Christianity: “[T]o believe that God created a plurality of worlds at least as numerous as what we call stars, renders the Christian system of faith at once little and ridiculous and scatters it in the mind like feathers in the air.” For those who attempted a reconciliation of such plurality with Christianity, Paine warned that “he who thinks that he believes in both has thought but little of either.” Paine, convinced of plurality, chose deism.

Many eminent figures agreed. The existence of extraterrestrials made belief in the particularity of Christianity an embarrassment. The poet Percy Bysshe Shelley found it easy to believe in extraterrestrials but, as a consequence, “impossible to believe that the Spirit that pervades this infinite machine begat a son upon the body of a Jewish woman.” John Adams wrote to warn Thomas Jefferson against hiring anyone at the University of Virginia who holds the “awful blasphemy” that the “great Principle which has produced…Newton’s universe…came down to this little ball, to be spit upon by the Jews.”

Scanning the 18th and 19th centuries, we find, then, two overlapping but opposing trends–one Christian and the other deist–united in one pluralist effort. Both sung endless paeans to a mighty God, creator of heaven and many earths, and both chiseled away at the doctrine of the Incarnation to make it fit such pluralism. Christians bent on saving Christianity from irrelevance cheerfully hacked away at the embarrassing particularity of the Incarnation until the doctrine itself became largely irrelevant. The deists, true to their Epicurean-Lucretian origin, simply gouged the Incarnation out of the cosmos as completely unsuitable to the new cosmology. The intelligentsia sided with the deists.

The revolution was not over, however. In the latter half of the 19th century, the intelligentsia shifted from deism to atheism. To be more exact, it simply embraced full-scale Epicurean-Lucretian materialism, now called Darwinism. Since the chance actions of matter were sufficient to create the universe, a deity was no longer either necessary or desirable. The deist god was given the bounce, replaced by the blind materialist forces of cosmic evolution. Atheism no longer needed the halfway house of deism. Secularization could now proceed at full throttle. And the belief in extraterrestrials was an essential part of the new materialist creed, just as it had been an essential part of the old one.

The Evidence of Absence

Only by the beginning of the 20th century was science advanced enough to move from speculation to the actual search for hard evidence. As amply documented by Steven Dick in Life on Other Worlds: The 20th Century Extraterrestrial Life Debate, by the end of the 20th century, scientists had demonstrated to all but the most zealously intransigent that–humble Earth excepted–our solar system was devoid of intelligent life and most likely devoid of any life. Further, as biologists discovered the ever-greater complexity of living organisms and the delicate balance of conditions that make them possible, it became clearer and clearer that fewer and fewer places in the universe could meet the conditions required for even the most rudimentary forms of life.

Yet the dismal result of the high-tech search for extraterrestrials only stirred advocates all the more, resulting in the optimistic but defensive battle cry: “The absence of evidence is not evidence of absence.” While this might warm the dwindling fires in the enthusiast’s heart, it pays little service to reason. To be blunt, since it was the negative result of a century-long search for aliens, the absence of evidence is evidence for absence. What else would it be?

A naysayer might ask, “But if what you’re saying is true, doesn’t the lack of scientific evidence for angels prove that angels don’t exist?” Such a riposte merely deflects attention from the seriousness of the self-inflicted wound. Again, whether or not angels exist, scientists were actively looking for extraterrestrials, convinced without a shred of evidence that they must exist. The simple truth remains: Over the span of the 20th century, science systematically eliminated the possibility of extraterrestrials in our solar system, and their existence elsewhere has dwindled from an absolute necessity to a dim chance.

Further, those who compare angels to aliens forget that angels are by definition immaterial beings. What kind of a scientific test would one devise to locate a being who, because it is not embodied, has no location? Extraterrestrials, on the other hand, are supposed to be material organisms; if they exist, we should be able to detect them the same way we detect any other physical body.

For the nonbeliever already convinced that angels don’t exist, to be forced to admit that he has no more reason to believe in aliens than in angels is an admission of defeat. This admission is all the more important precisely because extraterrestrials function for secularists as material substitutes for angels. In the great religion of secularism, aliens have now been reduced to, at best, a matter of faith.

Lessons for Theology

First, a humbling lesson for those inclined to hitch theological doctrines to the science of the day: Think how foolish we would appear today if the Catholic Church had modified its doctrine of redemption to make room for the solarians, venusians, mercurians, martians, and lunarians. We would be in the same speculative boat as Swedenborgians, Seventh-Day Adventists, and Mormons. The lesson? There’s nothing more dated than the ideas of those who insist on keeping their ideas up-to-date. The best remedy for theologians so inclined is a long, deep draught of the elixir of history, especially the history of science, where it becomes evident that today’s verities are often tomorrow’s absurdities.

Second, as we have seen, belief in the existence of extraterrestrials is not a modern thing, and that means it does not depend essentially on any advance in science. Rather, the belief stems from a particular metaphysical stance, not Christian but Epicurean in origin. As I argue long and hard in Moral Darwinism: How We Became Hedonists, such Epicureanism acts as an acid toward any religion but especially toward Christianity.

Third, Christians should be wary of leaning on revived forms of the sloppy logic of omnipotence, which arose after the publication of Tempier’s 219 Propositions in 1277. In its original form, it is a theological truism: “God is omnipotent; therefore God can create anything.” But all too soon, this became a very different proposition: “Since it is possible for God to create anything, then God must create everything possible; therefore, extraterrestrials must exist, and the doctrine of the Incarnation must be expanded accordingly.” This double inference is not only invalid but leads to foolishness. Would we say that since God is all-powerful, He must create fairies and also redeem them?

Fourth, Christians should be equally wary of the idea that God would somehow be a second-rate deity if He allowed human beings to be the only intelligent embodied beings in the universe, since that would mean a lot of wasted space. What frightens us into making such claims is, I believe, the immensity of space itself. But while the vastness of the universe rightly humbles us, its size means nothing to God, an immaterial intelligence. Since He has no size, it is all the same to Him whether He makes the universe as big as a pin or a pin as big as the universe.

A final, related point: Christians should not be cowed by the materialist’s logic of probability, which had its birth in Epicurus and Lucretius. The logic runs thus: Our sun is a star; since the number of stars is so vast, sheer probability demands that there must be other inhabited planets beyond our solar system. But probability does not demand any such thing, unless we think (with Epicurus) that the universe is governed by chance, and that, of course, would be a reason to give up our Christianity, not to rerig its cosmology.

I can already hear the parting objection: “But what would you do if extraterrestrials actually show up? It is possible, after all. And the Church hasn’t pronounced one way or the other.”

I am as prepared for the arrival of extraterrestrials as I am for that of elves, and for the same reason: All evidence points to their nonexistence, and yet it remains a very, very remote possibility–so remote that to change our central doctrines to accommodate either possibility would be folly.

Benjamin D. Wiker, a fellow with Discovery Institute, teaches theology and science at Franciscan University. His Moral Darwinism: How We Became Hedonists is now available from InterVarsity Press.