A Rational Faith
but sanctify Christ as Lord in your hearts, always being ready to make a defense to everyone who asks you to give an account for the hope that is in you, yet with gentleness and reverence;
—1 Peter 3:15
Peter says that after we sanctify the Lord God in our hearts, we are to be ready to give an apologia, a defense, to everyone who asks us a reason for our hope—not a feeling, but a reason. . . .
A while ago I was involved in a serious controversy involving a professor who had been teaching that biblical truth cannot be understood by reason but through some kind of mystical intuition. That is the position that was taken by the heretical Gnostics in the second and third centuries. They believed that their mystical apprehension of truth was superior to the Apostles’ because the Apostles relied on the mind. Relying on the mind is criticized by some who say that if you rely on the mind to understand the content of the Christian faith, you have submitted to the heresy of rationalism.
I asked this particular professor, “When you talk about rationalism, what do you mean? Are you talking about the Cartesian rationalism of the seventeenth century? Are you talking about the Enlightenment rationalism of the eighteenth century? Are you speaking about the Hegelian rationalism of the nineteenth century that deified reason itself?” He was completely unaware of those radically different types of rationalism. To say that you are a rationalist because Christianity is rational simply does not follow. One can be rational without being a rationalist, just as one can be human without being a humanist, or can exist without being an existentialist, or be feminine without being a feminist.
On the basis of Scripture, we must never negotiate the principle that the truth we receive from God is rational. It is not irrational or illogical. To say that the Word of God is irrational, contradictory, or absurd is to accuse the Holy Spirit of speaking with a forked tongue. As Peter said, “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” (2 Pet. 1:16). What they had witnessed was the sober truth of the Word of God, which is intelligible and reasonable for any reasonable person to embrace.
—R. C. Sproul, 1–2 Peter: Be All the More Diligent to Make Your Calling and Election Sure (Crossway, 2011), 120–121.