"The heart has reasons that reason does not have."
In general, we do not jettison our faith because we’ve encountered incontrovertible evidence against it. We set it aside for moral reasons.
I think of young friends who have moved away from home to a less restrictive environment and have begun to experience a new morality and consequent feelings of guilt. In time, they encounter a friend, professor or fellow-student who imparts his or her unbelief and gives them a rationale to quiet their conscience. Unbelief becomes an attractive option because it releases the tension between what they know in their hearts to be true and what they want to do. (We like to think of ourselves as rational beings, but in truth we're largely driven by passion and then must rationalize our actions.)
Listen to this admission by Aldous Huxley, one of the most influential philosophers of the 20th century. “I had motives for not wanting the world to have meaning; consequently assumed it had none, and was able without any difficulty to find satisfying reasons for this assumption. The philosopher who finds no meaning in the world is not concerned exclusively with a problem in pure metaphysics; he is also concerned to prove there is no valid reason why he personally should not do as he wants to do... For myself, as no doubt for most of my contemporaries, the philosophy of meaninglessness was essentially an instrument of liberation. The liberation we desired was simultaneously liberation from a certain political and economic system and liberation from a certain system of morality. We objected to the morality because it interfered with our sexual freedom."
I’ve observed this phenomenon for many years now and it’s been reinforced by countless conversations with men and women who argue cogently and vigorously against the faith, or certain aspects of the faith, and marshal their objections brilliantly. I listen and try to respond with kindness and persuasion, but it always seems to me that they protest too much and I actually feel like saying (though I have rarely done so) “And who are you sleeping with these days?”
An oversimplification? I don’t think so. Paul argues that unbelief is the final link in a chain that begins when we harden our heart against the witness of our conscience (Ephesians 4:17,18).
C. S. Lewis put a fine point on it: "What you see and what you hear depends a good deal on where you are standing. It also depends on what sort of person you are." Put another way, we don't see things as they are. We see things as we are. It's the pure in heart that see God.
 Aldous Huxley, "Confessions of a Professed Atheist," Report: Perspective on the News, Vol. 3, June, 1966, p.19.
 Similarly, Israel’s poet insists that unbelief is the product of moral declension and not rational argument: “The fool has said in his heart there is no God” (Psalm 54:1). Here, the writer selects a specialized word for “fool” that refers not to an ignoramus, but to someone who has turned his face away from the moral law and who then becomes a practical atheist, i.e., he behaves as though God does not exist and his moral will has not been revealed.