By all means! It is intensely rational. Now, maybe I can confuse things for everybody by repeating a question that somebody asked me just this week. They said, "Is it true of you, R.C., that you are a Christian rationalist?" I said, "By no means! That's a contradiction in terms. A rationalist is somebody who embraces a philosophy, a system of philosophy, that sets itself over and against Christianity." And while I demure at that point of being called a rationalist, but I'd certainly embrace the idea that Christianity is rational.
What does it mean to be rational? To ask me if Christianity is rational is to ask me if Christianity is coherent? Is it intelligible? Does it make sense? Does it fit together in a consistent pattern of truth, or is it the opposite of rationality is it irrational? Does it indulge in superstition and embrace contradictions and absurdities?
There are a lot of people, even Christians, who believe that Christianity is manifestly irrational. I think that's a great tragedy. The God of Christianity addresses people's minds. He speaks to us. We have a Book that is written for our understanding, and man cannot understand something that is irrational or that violates the canons of rationality. When I say that Christianity is rational I do not mean that the truth of Christianity in all of its majesty can be deduced from a few logical principles by a speculative philosopher. There is much information about the nature of God that we only can find because God Himself chooses to reveal it. He reveals these things through His prophets, through history, through the Bible and through His only begotten son, Jesus.
But what He reveals is intelligible; we can understand it with our mind. He doesn't ask us to crucify our minds to become Christians. There are people who think that to become a Christian, one must leave their brain somewhere in the parking lot and jump into the darkness and pray that Jesus will catch them. The only leap the New Testament calls us to make is not into the darkness but out of the darkness, into the light, into that which we can indeed understand.
That does not say that everything that the Christian faith speaks of is manifestly clear with respect to rational categories. I can't understand, for example how a person can have a divine nature and a human nature at the same time as we believe about Jesus. That's a mystery. But it's the same thing in the scientific world. I don't understand the ultimate force of gravity. These things are mysterious to us but they're not irrational. It's one thing to say, I don't understand from my finite mind how these things work out, and it's another thing to say, these things are blatantly contradictory and irrational, but I'm going to believe them anyway. That's not what Christianity does. Christianity says there are mysteries, but those mysteries cannot be articulated in terms of the irrational. To do so would mean we've moved away from Christian truth into irrationality.