The atheist asks the Christian how God can exist as three persons – Father, Son and Spirit.
The Christian replies that he doesn’t fully understand the answer to this, pointing out that an infinite being such as God cannot be fully grasped by a human, finite, mundane intelligence.
The atheist is unsatisfied, and says that the Christian is committing a copout. “How, after all, can you expect me to believe in your God when you don’t even understand him? I point out logical incoherencies in your God, and all you can say is you can’t expect to understand the infinite.”
This is a fictional anecdotal example what I’m going to call the incomprehensibility fallacy – who it is that commits the fallacy hasn’t been named.
I think it is often said by Christians that we simply don’t understand, and thus can’t give you an answer, and that this is because God is totally other-worldly, immaterial and infinite. And it is often said by atheists that this is a copout.
But consider this. There are many, many things I don’t understand about Australia’s legal system. But I’m quite convinced that it exists – and justly so (the evidence is reasonably overwhelming). To say that the fact that I don’t understand the Australian legal system is a good reason to think that it doesn’t exist is pretty unreasonable. You might even call it a sort of “incomprehensibility fallacy”. There are all sorts of things whose existence I am convinced of, and that I don’t understand and do not even expect to understand: my own circulatory system, the discipline of economics, the universe at large, atoms, and of course, women.
The question is not: “can you give an exhaustive and comprehensive theory about this object and all its qualities?”
The question is: “do you have sufficient evidence to be able to say with confidence that this object (with at least x number of essential qualities) exists, whatever other qualities it may possess?”
Of course we don’t understand everything about God. But I do believe we have enough evidence to be able to say confidently that he exists, and to understand certain characteristics that he has: that he is good, that he loves all people, that he created the universe, that he is all powerful, and a few other things.
We also know that he became human in the person of Jesus, died, and rose again. Some of the consequences of this are very hard to grasp, though. If God is eternal, and he existed on Earth for a time as a man, then it is necessary that God was at once both in Heaven and on Earth. It is from here that all the deductions have to begin, to bring us towards the doctrine of the Trinity. The Trinity is a very confusing and often seemingly incoherent concept. But it is a metaphysical difficulty that is necessitated by irrefutable empirical facts. The fact that we cannot understand it does not license us to throw it away entirely, because it is not the theory’s tidiness and comprehensibility that causes us to believe it; it is the theory’s grounding in indispensable premises.