Is religion a bunch of nonsense, unverifiable statements that have no relation to reality? Is it like one’s favorite ice-cream flavor? You may say that vanilla is your favorite, but it doesn’t make sense to argue that someone else ought to prefer vanilla. He either does or doesn’t. All you can do is make fun of his choice.

Is this the way theology proceeds? Can we make any arguments, or is it all a matter of shouting and claims of blasphemy?

St. Thomas deals with this in I:1.8, “Whether sacred doctrine is a matter of argument?”

In any constructive argument, there are principles and derived conclusions. The principles are not argued about. Physics doesn’t argue about causality but assumes it. Logic presumes the principle of non-contradiction. It can’t be proven, and therefore shouldn’t be argued about. Aristotle goes so far as to say those who doubt non-contradiction should be exiled! Sciences don’t question their own principles, but leave that to higher sciences. Astronomy doesn’t dispute about straight lines but gets them from geometry.

What if you don’t share principles?

What if someone else doesn’t share your principles? You can’t argue with them, since the argument proceeds by showing how the conclusion comes from the principles. There’s no point arguing about cause and effect in nature with someone who doesn’t accept causality.

What can you do if someone doesn’t accept your principles? You can’t argue them out of their position, because they’ll deny all the tools that you would use to prove your point. I once argued with a woman who denied the principle of non-contradiction. Whenever I made a particularly good point, she would just tell me that I hadn’t meditated enough. What can one do?

Thomas says:

the highest of them (the sciences), viz. metaphysics, can dispute with one who denies its principles, if only the opponent will make some concession; but if he concede nothing, it can have no dispute with him, though it can answer his objections.

In theological argumentation, if you are starting with the Bible, you can’t argue with someone who doesn’t accept the Bible. There are no common principles. You prove the Catholic doctrine of the Eucharist from the Gospel of John–well and good, but what does your opponent care about the Gospel of John? All you can do is answer objections, perhaps denying the impossibility of the Real Presence by borrowing Aristotelian categories, as Thomas does.

When talking to people who do not have faith, all you can do is answer objections. This can be very good! What if someone won’t believe because of difficulties over free will? Show how divine knowledge and free will are not contradictory. This opens up the possibility of faith. Where it goes from there, God knows.

The objections can’t be true

How do we know that the objections can be answered? Thomas ties this to the truth of faith. If it’s true, it cannot be contradicted. Truth has no contradiction!

Since faith rests upon infallible truth, and since the contrary of a truth can never be demonstrated, it is clear that the arguments brought against faith cannot be demonstrations, but are difficulties that can be answered.

Here you see the optimism that Chesterton speaks of: If the faith is true, the objections cannot be true, and you can confidently work out the error, if only you are patient enough.

But there is also the reserve to know that the principles of faith can’t be proved. You either accept them or you don’t. Having accepted them, we can argue, but before you do that, I can only answer objections.

Why it has to be this way

Kant argues against the cosmological proofs for the existence of God because they extend categories for the understanding of the phenomenal realm, which we can see, to the noumenal realm, which we cannot. This a fair point, but it also tells us why faith has to be the way it is. Why can’t we just prove it? Thomas argued earlier that you need theology/sacred doctrine in the first place because the destiny of human beings is transcendent. It lies beyond the perceivable universe. If this is true, any knowledge of that destiny will also be from beyond the perceivable universe. It will have to be faith.

A religion that could be proved wouldn’t be a faith. It would be a therapeutic technology that started within the universe and stayed right there. Any religion that saves must be a faith.