Psalm 14:1 (NKJV)
14 The fool has said in his heart, �There is no God.�
They are corrupt, They have done abominable works, There is none who does good.

The sinner here described. He is one that saith in his heart, There is no God; he is an atheist. "There is no Elohim, no Judge or governor of the world, no providence presiding over the affairs of men.' They cannot doubt of the being of God, but will question his dominion. He says this in his heart; it is not his judgment, but his imagination. He cannot satisfy himself that there is none, but he wishes there were none, and pleases himself with the fancy that it is possible there may be none. [Matthew Henry Commentary]

As an atheist university professor, Dr. Holly Ordway, was convinced that by definition faith is utterly irrational. She would eventually become a Christian, but prior to her conversion she used the following analogy to explain why, as an atheist, she could not consider the option of believing in Jesus and going to heaven:

Imagine that you tell me, "If you believe that there's an invisible pink unicorn in the sky, I'll give you a new BMW." I see the car in the parking lot; you jingle the keys in your hands. If I can believe what you want me to believe, the new car is mine. Cool! But it's a waste of time: I know there's no unicorn. No matter how much I want that car, I am incapable of believing something contrary to reason in order to get it. Believing something irrational on demand to get a prize: that is what the evangelical invitation to "accept Jesus and get eternal life in heaven!" sounded like to me.

Despite her skepticism, she went on to accept Christ and to write a book about her conversion experience called appropriately Not God's Type.

[Holly Ordway, Not God's Type (Ignatius Press, 2014), page 9]