I often run into people who think that faith is by definition an irrational belief, in that it is not backed up by evidence the way scientific beliefs are.  This is a fundamental misunderstanding of the way informed Christians understand faith.  (Unfortunately, may uninformed Christians help to perpetuate the error themselves.)  So what is faith, and how does it relate to reason?

A Rational Person

In the Bible, faith is simply trust. You can trust something or someone for good reasons, bad reasons, or no reason. The only faith the apostles were interested in was trust in Jesus as God’s Messiah held for good reasons: the eyewitness testimony to His resurrection confirmed by His fulfillment of Old-Testament prophecy. To define faith in advance as irrational is to beg the question.  In fact, there is no human belief that does not depend on faith for its validity.  Not one.

Augustine understood that all truth claims are based on faith. Scientific truth claims are no exception. You cannot have a rational proof of the laws of logic that does not depend on their validity before you start the proof. You cannot put the scientific method in a test tube. You cannot prove that our senses, and the instruments that extend them to make scientific observations, are in touch with a real external world. You have to trust that these things are true. Science cannot even get off square one without faith in the ultimate rationality of the universe and the ability of the human mind to perceive it.

Now, there are good reasons for trusting those things, but it is trust, i.e., faith, nonetheless. For Christians there is an additional rationale for putting our trust in the rationality of the universe and (potentially) of human minds: our belief that it was created by a rational God who made us in His image.  Our minds were made on the pattern of the Mind that wrote the equations by which the universe works.  Apart from this foundation, the rationality and intelligibility of the universe is an insoluble mystery.  With it, our ability to do science makes perfectly good sense.

Aliens responding to the irrationality of rationalism.


You have to put your faith in something.  You do not have a choice about that.  You can put your faith in solid things that have good support or stupid things that are irrational.  You can, in other words, have grounded faith or blind faith. Each act of belief has to be judged on a case by case basis to discover which it is. To define faith as “irrational” in advance is to beg the question.

Guess which kind of faith that is?

Donald T. Williams is R. A. Forrest Scholar at Toccoa Falls College. A past president of the International Society of Christian Apologetics, he is the author of twelve books, most recently Deeper Magic: The Theology behind the Writings of C. S. Lewis (Baltimore: Square Halo Books, 2016), An Encouraging Thought: The Christian Worldview in the Writings of J, R. R. Tolkien (Cambridge, OH: Christian Publishing House, 2018), and The Young Christian’s Survival Guide: Common Questions Young Christians are Asked about God, the Bible, and the Christian Faith Answered (Cambridge, OH: Christian Publishing House, 2019). Order from the publisher or Amazon.