My answer is a mixed one. It is yes and no. It all depends on how a person handles Scripture in their apologetic approach. If they relegate the Bible as a secondary authority, or worse as no authority at all, then they are treading the slippery slope of rationalism.
But if apologetics is done in its proper form, as Peter says, we are merely giving a reasoned response—an answer—for what we believe from Scripture (1 Peter 3:15). Let me give you five quick thoughts on this question. The first four deal with why we can’t allow apologetics to fall prey to rationalism and the last thought is a warning about an attitude that might be behind the question itself regarding apologetics and rationalism.
First, rationalism is a form of idolatry.
It would be wrong to see our human reason as the ultimate authority—a role to which God alone holds the rightful claim. This would result in our reshaping the Bible to fit our own expectations, much like what Thomas Jefferson did with the Gospel accounts. We are not God’s editors. He’s already went to print. Our thoughts about God are subject to the Word of God and not the other way around.
Second, rationalism doesn’t work.
No one should need much of an argument to know their reasoning abilities are limited. Theologians refer to this as the Noetic effects of the fall, which means that every part of the human experience is effected by sin, including our minds. We forget things, we misunderstand things, we misrepresent things. A simple look at the limits of our reason demonstrates our need for divine revelation. We do have rational abilities that are rather impressive, some more than others, but they are all limited.
Third, whose rationalism?
This could quickly slide into an entirely subjective view of truth. Whose reason is to be trusted? Is one group’s reason more valid than another? Some arguments seem more compelling to some than others. Attend any debate and you will often see a divided audience responding to the same claims. Who can be trusted to speak with the voice of Reason?
Fourth, if we didn’t know that God created the world, that in the beginning was the Word, then we wouldn’t have a foundation for reason.
It’s because the source of the created world is himself rational that we have a basis to think there is a rational order to the world and that we have the ability to get at it. We didn’t sit around and reason ourselves into the belief of God as creator, although Scripture does speak to an innate knowledge of God from the created order (Romans 1). We know all these things from Scripture.
Finally, I think there can be an unhealthy attitude lingering beneath the question of whether or not apologetics is rationalism.
Sometimes I hear people push back against reasons for believing the Christian faith because they feel that using an intellectual approach is itself sinful, or represents a lack of trust, or is unfaithful to the Bible. We must remember that God is the source of the rational order of the world and that he has endowed us, as those created in his image, with the ability to study, understand, and articulate truth.
If not careful, a person could untintentionally swing the pendulum away from rationalism towards irrationalism. This would result in someone saying, “I just believe what I believe it doesn’t have to make any sense.” This could easily lead to the kind of irrational beliefs that many neo-orthodox thinkers held to in the stream of theological existentialism. Just take a blind leap of faith and you will be okay, they might think.
This isn’t a biblical option either. God doesn’t call for a blind leap of faith. That is not the biblical depiction of what faith is.
That’s why I love the definition of faith given by R.C. Sproul, “Faith is well-reasoned trust.” I would add that faith is well-reasoned trust in the God who has revealed himself. Just as Paul encouraged the Corinthian church to order their worship services after the character of God, because “God is not a God of disorder” (1 Corinthians 14:33), we too should pattern our thinking after the character of God who is the very ground of reason itself (Romans 12:1-2).
This doesn’t result in rationalism, but in a well-reasoned trust in the God who is there, and who is not silent.