Thomistic Arguments for Christianity


Saint Thomas Aquinas is famous for his philosophical proofs for the existence of God, but proving theism does not prove Christianity. Fortunately, Aquinas did not stop there. Although they are less well-known, and sprinkled throughout several of his works, Aquinas extended his apologetic arguments to the truth of Christianity itself.

In many apologetic systems (e.g., McDowell, Geisler, or Montgomery), the key to proving the truthfulness of Christianity (whether or not first proving theism) is arguing for trust in the Bible. In fact, they are usually treated as equivalent. But arguing for Christianity and arguing for the Bible are two different things. The Bible is a product of Christianity, not vice versa.

Such is not Aquinas’s method. He does not argue for trust the Bible per se. One does not find in his apologetic system much in the way of arguments from archaeology, scientific verification, historical reliability, or manuscript transmission. What he did argue for was the truth of the tradition that was the Bible’s source. Not only does this “cut out the middle man,” it also makes better use of miracles as evidence (since using biblical miracles to prove the Bible can become circular if one is not careful).

Miraculous Confirmation

Miracles in General

Miracles are kind of a hinge between arguments for God and from God. If miracles are acts of God by definition (which Aquinas believes they are), then a miracle would prove God. But it is difficult to make that move if one is not already convinced that a God that can do miracles exists. After all, strange things happen all the time, and without a theistic context, it is easy for modernists to write miracle claims off. Thus, in the classical apologetic method, miracles follow after proofs for God, and take on the function of confirming God’s messengers.

In both of his most famous works (Summa Theologiæ and Summa Contra Gentiles), Aquinas basically switched to discussing Christian doctrine once the existence of God has been demonstrated. However, even though he did not write as elaborately or systematically concerning proofs for the Christian faith, he did not leave the issue hanging. In both Summas, Aquinas asserts that miracles are used to confirm the truth of Christianity:

“The working of miracles is ascribed to faith for two reasons. First, because it is directed to the confirmation of faith, secondly, because it proceeds from God’s omnipotence on which faith relies. Nevertheless, just as besides the grace of faith, the grace of the word is necessary that people may be instructed in the faith, so too is the grace of miracles necessary that people may be confirmed in their faith.” (ST

“The divine Wisdom itself, which knows all things to the full, has deigned to reveal to men. It reveals its own presence, as well as the truth of its teaching and inspiration, by fitting arguments; and in order to confirm those truths that exceed natural knowledge, it gives visible manifestation to works that surpass the ability of all nature.” (SCG 1.6.1)

The Miracle of the Resurrection

Of the many miracles God has used over the centuries to pick out his spokespeople, the greatest was the resurrection of Jesus Christ. Aquinas says the resurrection of Christ was in fact necessary for coming to faith:

“Secondly, for our instruction in the faith, since our belief in Christ’s Godhead is confirmed by His rising again, because, according to 2 Corinthians 13:4…” (ST 3.53.1)

After dedicating an entire article to various apologetic issues over the value of the resurrection, Aquinas then says,

“Each separate argument [for the risen Christ] would not suffice of itself for showing perfectly Christ’s Resurrection, yet all taken collectively establish it completely, especially owing to the testimonies of the Scriptures, the sayings of the angels, and even Christ’s own assertion supported by miracles.” (ST 3.55.6.R1)

Note again Aquinas’s assertion that miracles support the divine message.

The Miracle of the Church

For Aquinas, miracles include the very existence of the Church. The Christian Church was founded on miraculous claims, and so its genesis is difficult to explain were they absent. Too many people died without recanting their miracles stories for them to have been lies.

“Everything that the Saints believed and handed down to us concerning the faith of Christ is signed with the seal of God. This seal consists of those works which no mere creature could accomplish; they are the miracles by which Christ confirmed the sayings of the apostles and of the Saints.”  (“Exposition of the Apostle’s Creed” – Prologue)

Aquinas says the Church remains a verifiable miracle even today. So, even if someone questions miracle stories of old, the Church itself continues to show Christianity’s miraculous nature – for without miracles, ongoing conversion would be even more miraculous:

“If, however, you would say that no one has witnessed these miracles, I would reply in this manner. It is a fact that the entire world worshiped idols and that the faith of Christ was persecuted, as the histories of the pagans also testify. But now all are turned to Christ—wise men and noble and rich—converted by the words of the poor and simple preachers of Christ. Now, this fact was either miracle or it was not. If it is miraculous, you have what you asked for, a visible fact; if it is not, then there could not be a greater miracle than that the whole world should have been converted without miracles. And we need go no further. We are more certain, therefore, in believing the things of faith than those things which can be seen, because God’s knowledge never deceives us, but the visible sense of man is often in error.”  (EAC – Prologue)

Aquinas says much the same thing here, noting that so many different kinds of people not only believed, but gave up pleasures in this life for things unseen in the next:

“When these arguments were examined, through the efficacy of the abovementioned proof, and not the violent assault of arms or the promise of pleasure, and (what is most wonderful of all) in the midst of the tyranny of the persecutors, an innumerable throng of people, both simple and most learned, flocked to the Christian faith. In this faith there are truths preached that surpass every human intellect; the pleasures of the flesh are curbed; it is taught that the things of the world should be spurned. Now, for the minds of mortal men to assent to these things is the greatest of miracles, just as it is a manifest work of divine inspiration that, spurning visible things, men should seek only what is invisible. . . .” (SCG 1.6.1)

Thus it is that the kinds of miracles recorded in the Bible need not be repeated:

“Now, that this has happened neither without preparation nor by chance, but as a result of the disposition of God, is clear from the fact that through many pronouncements of the ancient prophets God had foretold that He would do this. The books of these prophets are held in veneration among us Christians, since they give witness to our faith. This wonderful conversion of the world to the Christian faith is the clearest witness of the signs given in the past; so that it is not necessary that they should be further repeated, since they appear most clearly in their effect. For it would be truly more wonderful than all signs if the world had been led by simple and humble men to believe such lofty truths, to accomplish such difficult actions, and to have such high hopes.”  (SCG 1.6.1)

Even so, God has not left the world without continuing miraculous activity in His Church:

“Yet it is also a fact that, even in our own time, God does not cease to work miracles through His saints for the confirmation of the faith.”  (SCG 1.6.1)

It should also be noted that Aquinas’s use of the Church’s existence and activity as miraculous confirmation of the truth of Christianity actually gains strength as the years go on!


Aquinas was the Church’s best theologian and apologist because he utilized the best philosophy when dealing with matters addressable by philosophy. But Aquinas also used historical evidence when dealing with historical issues. Once showing (via philosophy) that there had to be a single, simple, omnipotent, creator God, Aquinas went on to prove which purported revelation was really from that God.

Because God had to use human means to convey human knowledge – and these means are by definition reproducible by mere humans as counterfeit revelations – God chose to back up the words of his spokesmen with acts that no mere human could produce. These “motives of credibility” are not determining causes that force belief, however. Rather, they are strong enough pointers to the truth that they give a people the intellectual freedom to choose belief without resorting to blind consent.


8 thoughts on “Thomistic Arguments for Christianity

  1. Hi, Doug,

    First of all, congratulations to you and your wife on the birth of Dante!! Great name choice! 🙂

    Second, even though we’re friends on Facebook, until the last couple of days, somehow, I had not regularly visited your site *here* for almost a year– which is hard for me to believe, and all to my loss! I’ve really been missing out on some very good, thoughtful writing here! I’m glad that I stopped by again, after not doing so for so long (my chronic pain issues have kept me literally down, and “out of the loop” on many good things, this entire year…). I will reading here much more often in the weeks and months to come, Lord willing. The posts that I’ve read here, over the last two days, comprise what is simply some of the best Christian writing available anywhere, on the internet *or* in book form, period. Very, very helpful! Thank you and God bless, brother!

  2. I wonder how Aquinas would respond to a Mormon, Hare Krishna, or Muslim who had faith in their religion because of many Mormons, Hare Krishnas, and Muslims who passed over temporal pleasures for the sake of unseen future joy. 1. Is their faith a virtue? 2. Does their faith count as knowledge if these religions are true? 3. What is it that makes the Christian faith epistemically preferable against the others?

    While Aquinas was very rigorous with natural theology, it seems that contemporary apologists like Craig, Moreland, and Licona offer more rigor and clarity when it comes to arguing for Christianity among the theisms.

  3. Jordan,

    First, dying for one’s faith is all well and good unless one knows it is a falsehood. That’s one large difference. Also, Aquinas was quite aware of Islam (having written Summa Contra Gentiles to Christian missionaries against Islam). What miracles can a Muslim or Mormon point to? None. What historical facts are there surrounding Krishna? Exactly. These religions make the case against themselves. I doubt Aquinas would have even considered them worth commenting on.

    Modern apologists do well against modernists because they are dealing with a very different mindset. Craig uses analytic modern philosophy in order to appease his opponents, for example. Licona’s main contribution has been to try to deal with the resurrection in a way that will satisfy modern historical skeptics – not a big issue in Aquinas’s time because he did not have to deal with historical relativism and such.

  4. Thanks for the response Doug. I do agree that the dying for one’s faith thing is a good argument for the resurrection, because they were in a position to know. It seems to me that a historical argument for Jesus and his Resurrection is unavoidable. Aquinas (if I’m not mistaken) implies that the mere “conversion of the world” would be sufficient as an argument. But a Muslim could appeal to Muslim conversions too.

  5. Beyond the traditional arguments respecting the origin of the Catholic Church through the preaching of humble men, and the rapid spread of the Church throughout the Roman Empire absent military of worldly resources; the following CUMULATIVE considerations call for an explanation – especially in light of the wide array of prophecies respecting the origin, spread, and scope of the messianic kingdom which antedate the Christian era.

    The society of the Catholic Church is a complex of doctrine, worship and government maintained as a unity for over 20 centuries. It encompasses a wide array of persons, cultures, and languages as a single world-wide society; even though many of its citizens never come into contact with one another due to geographical or temporal distance. In short, though penetrating the widest array of cultures and epochs, the Catholic Church remains identifiable as such.

    The Catholic Church transcends a biological community. It transcends family, clan, ethnicity and race – the most common occasions of human division and conflict. The Church, instead, tends to reunite all men despite differences in race, color, language. Its societal scope is superimposed upon the geography of earth. The globe is a network of diocese functionally and organically united around their bishops, and universalized by virtue of the unity of these bishops with the successor of Peter in Rome.

    The Catholic Church extends through history and perseveres despite the vicissitudes of history. It withstands enemies from within, such as sin and incompetence among both laity and clergy. It remains despite overwhelming enemies from without such as persecution, imperialism, modernism, etc. Even in its weakest moments, the Church is always breaking free of imprisonment within its historical contexts and conditions (Roman Empire, feudal Europe, modern states). In short, where most human cultures and religions dissolve or die, or yield to syncretism; the Catholic Church does not; but rather, maintains both a consistent organic structure, as well as a consistent body of doctrine free of dogmatic contradiction, for 20 centuries.

    The Catholic Church is holy in her doctrine, mission, and means of sanctification. Like a leaven in society, raising morals and the dignity of persons, the Church holds the loftiest moral ideals, such as the evangelical council’s (poverty, chastity and obedience) which run opposite to man’s natural inclinations; and, further, maintains her moral positions even when the surrounding culture – including fellow Christians – give way in the face of shifting mores. Though she harbors many sinners (as would be expected in a hospital for sinners), she also produces saints of extraordinary holiness. Simply by virtue of her general ranks, the Catholic Church is easily understood as the greatest charitable agent within Western civilization – both past and present.

    These factors are drawn primarily from the great Jesuit theologian, Rene Latourelle’s seminal work “Theology of Revelation”, which I consider to be THE watershed theological treatment of that most fundamental category of Christian theology: namely, divine revelation. Latourelle powerfully summarizes the force of these considerations on behalf of the trans-historical, trans-geographical society of the Catholic Church as follows:

    “All these traits, taken together, make the Church an exceptional society among human societies. No society, in the recorded testimony of history, sociology, or psychology, can thus offer the SIMULTANEOUS spectacle of an internal and external unity, universality, perpetuity, stability, holiness, and fecundity that the Church can offer. All this, considered TOGETHER and QUALITATIVELY, completely transcends the common experience of human societies.” [Theology of Revelation, Pg. 422]

    I find the case to be quite strong.

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