First, here are some definitions for clarification, courtesy of Merriam-Webster Online. “Rational” means relating to, based on, or agreeable to reason. Being in accordance with reason. “Rationalism” is reliance on reason as the basis for establishment of religious truth.
Christians are not rationalists. Theology that is authentically Christian is not rationalistic. Christians believe their religion to be revealed, not derived from human reason. As St. Paul puts it,
“my speech and my preaching were not with persuasive words of human wisdom, but in demonstration of the Spirit and of power, that your faith should not be in the wisdom of men but in the power of God.” (I Corinthians 2:4-5)
St. John writes similarly:
That which was from the beginning, which we have heard, which we have seen with our eyes, which we have looked upon, and our hands have handled, concerning the Word of life – the life was manifested, and we have seen, and bear witness, and declare to you that eternal life which was with the Father and was manifested to us – that which we have seen and heard we declare to you (I John 1:1-3a)
And the Word became flesh and dwelt among us, and we beheld His glory, the glory as of the only begotten of the Father, full of grace and truth. (John 1:14)
And St. Peter writes:
For we did not follow cunningly devised fables when we made known to you the power and coming of our Lord Jesus Christ, but were eyewitnesses of His majesty. 17 For He received from God the Father honor and glory when such a voice came to Him from the Excellent Glory: "This is My beloved Son, in whom I am well pleased." 18 And we heard this voice which came from heaven when we were with Him on the holy mountain. (2 Peter 1:16-18, referring to the Transfiguration, accounts of which event are in Matthew 17:5, Mark 9:7, and Luke 9:35)
Christians are not rationalists. But they are rational. They base their faith upon what has been heard and seen and touched. Christians are followers of the Word Made Flesh, where “Word” does not mean a sequence letters between spaces and having a certain definition. No, the Greek “Logos”, usually translated “Word,” actually means God’s Reason. “Logos” implies, moreover, not an inarticulate or inchoate Reason, but one capable of being set forth. When the Word (God’s Reason) dwells in human flesh, in the Man Jesus, then it He is even capable of expressing itself Himself in human terms.
God’s Reason is of course high above all human reason – but note carefully: above it, not beneath it! God’s Reason does not fail the elementary tests of rationality. To the contrary, God’s Reason first meets those criteria and then far exceeds them. Where revelation boggles the mind and our poor brains cannot follow, the “problem” is not darkness, but a superabundance of Light, inexhaustible Light.
Put another way, God does not contradict Himself. That’s the first way you know any theology which does is a human invention, not divine. There is no contradiction in God.
Observe, if you please, what happens when people do accept a theology that contradicts itself. I am not speaking here of paradox, which is only a form of irony, nor of an only apparent contradiction, as evidenced by the fact that somebody, somewhere, can explain it away. I’m speaking of a flat-out, genuine contradiction, incapable of being resolved by anybody, a square triangle, a rock too heavy for God to lift.
Well, then, the first thing that happens when you accept a contradiction in theology (or any other field) is that you turn it into meaningless mush. That’s because each side of the contradiction cancels out the other. If we call these two sides of the contradiction A and B, then we can see a couple of examples:
A. This is a square.
B. It is triangular.
A. God is Love.
B. God hates sinners.
A. God chooses whom to save. It’s 100% up to Him and there’s nothing anybody can do about it. Ultimately, the ones He chose do end up being saved and only the ones who end up being saved are the ones He chose.
B. God does not choose whom to condemn.
In each of these cases, as in every contradiction, we see A and B cancelling each other out. And when that happens, we are left with nothing. We are left with empty words, bereft of meaning. We are left with incoherence.
But that’s only the first thing that happens. The next thing is that if you accept a contradiction in theology and then say each side of it is supported by Scripture, you knock the bottom out of Sola Scriptura. Because the first principle implied by Sola Scriptura is that anything which contradicts the Word of God must be rejected. Thus, if your interpretation of Scripture makes Scripture to contradict itself, then, according to Sola Scriptura, your interpretation ought to be tossed out. By not tossing it out, by retaining it despite the principle of Sola Scriptura, one flouts that doctrine, defies it, puts his contradictions above it. (Isn’t THAT rationalism?)
It gets still worse, because by accepting a contradiction in theology and asserting that both sides of the contradiction are supported by Holy Scripture, it’s not just the doctrine of Sola Scriptura one knocks the bottom out of (this wouldn’t bother Orthodox Christians anyway) but Scripture itself. This is because to the extent one makes the Bible incoherent, it cannot be used for anything, and especially cannot be used to settle any doctrinal dispute. If any contradiction of Scripture by Scripture is acceptable, why not all? As I've said before, every heretic comes armed with Scripture to contradict Scripture, and the devil, too, when he tempted Jesus in the wilderness. By what criterion will we now decide whose contradictions are acceptable?
To the extent the Bible is interpreted as incoherent, to that extent it ceases to be revelatory. Gibberish is no longer revelation nor a record of revelation – but Christianity is all based upon revelation. The damage, then, is not merely to the Bible, but to Christianity itself.
Could it get even worse? Yes, because of course we have, unwittingly, a reverence issue going on here, too. To say, in effect, that the Holy Scriptures contradict themselves is to say, in effect, that the Holy Spirit does.
Just don’t go there. Search out an interpretation of the Holy Bible that allows it to stand as a consistent, coherent, reliable, and revelatory whole, as the Word of God always is, in Whom there is no contradiction.