Victor Reppert links to an argument that no idea of God is coherent. Thesis one:
The words used to describe the deity seem at first sight to make sense. He (for it’s almost always “he”) is all-powerful, all-loving, all-knowing. He is the source of morality, and will punish the wicked and reward the deserving for all eternity. However, when unpacked, these phrases have no more meaning than Lewis Caroll’s Jabberwocky.
This might make for an interesting dialogue with theologians. St. Thomas, for example, argues that because…
God is simple, and exists, we attribute to Him abstract names to signify His simplicity, and concrete names to signify His substance and perfection.
God is known both though abstract names (justice, personhood, dignity) and concrete names (person, just). There is therefore some incoherence in our idea of God so far as we have no third class of terms, transcending the abstract and concrete, which unifies both in a single concept or reality. This problem of abstract and concrete naming is simply an extension of the more basic problem that, for St. Thomas 1.) God is only act (or “Pure Act”) and 2.) all subjectivity is potency. There is, therefore, no subject of pure act. If by “God” we mean that there is some subject with divine attributes, then there is no God. We can say God exists, but not that there is a subject of the divine existence. Do these ideas cohere? Don’t we have more the sense of forcing ideas together and holding them there like two repellent poles of different magnets? I’m pretty confident that what St. Thomas is saying here is true, but this does not mean that I think his idea of God comes together in a perfectly coherent way. Cajetan makes this point in a particularly emphatic way: and tough he makes the point in relation to the question whether God is Absolute or Relative (from trinitarian relations), the point he makes applies to what we have said here to the question whether God is concrete or abstract:
We err when, setting down the division between the absolute and relative as a principle, we imagine that this distinction between the absolute and relative is somehow prior to God; and that we consequently believe that we must place him in on one side of the distinction or the other. He is both opposites, since God is prior to being and to any of its oppositions: he is above being, above one, etc.
Cajetan even argues that this is necessary:
It is necessary that this be the case: for it is necessary that watever is most simple in itself be maximally one, and that one adequate formal ratio correspond to it, otherwise there would not be one thing that was per se and commensurately universal intelligible by which everything is known.
For Cajetan, the very possibility of distinction requires that this rest on an intelligible basis that transcends distinction. So far, this is pretty commonly accepted metaphysics. But the thomistic tradition – at least the part that goes through Cajetan – goes further by pointing out that if some reality is the basis for intelligible distinction, it must be prior to any of these distinctions. The basis of all distinction cannot be some subject falling on one side of the distinction. But even “being” is for us one side of a distinction, which is precisely why the first principle of our thought is the principle of contradiction. Thus, on this argument, the basis of our knowledge is a third option beyond p or ~p.
This points to an interesting and significant disagreement between atheists who give arguments from incoherence and natural theologians. We disagree about the significance of the lack of coherence we have in our notions of God. For the atheist, our inability to form a single, unified – or coherent – concept that brings together all that we know about God proves the idea is ridiculous and unthinkable; for the others, it is exactly what is necessary for thought, that is, (to develop an idea in Chesterton’s Orthodoxy) thought requires an unthinkable basis.