What is self-deception, anyway? Self-deception is playing dumb. It means pretending to ourselves that we don’t know what we really do; it means playing at being ignorant even though we are really in the know. I suggest that we human beings play dumb with God. We lie to ourselves, and one of the things we lie about is our knowledge of His reality. Psalm 14 opens with a remark which is often misunderstood: “The fool says in his heart ‘There is no God.'” In this comment the Psalmist isn’t calling the man a fool for thinking that there is no God, but for telling himself that there is no God even though deeper in his mind he knows better. Unbelievers do not disbelieve, they reject. In the strictest sense, it isn’t God who doesn’t exist; it is atheism which doesn’t exist.
Paul expresses the same view in the first chapter of the letter to the Romans. I do not ask anyone to believe it just because it is in the Bible; I only call attention to an interesting claim (which is also my claim) and ask the reader to think about it.
 For the wrath of God is revealed from heaven against all ungodliness and wickedness of men who by their wickedness suppress the truth.  For what can be known about God is plain to them, because God has shown it to them.  Ever since the creation of the world his invisible nature, namely, his eternal power and deity, has been clearly perceived in the things that have been made. So they are without excuse;  for although they knew God they did not honor him as God or give thanks to him, but they became futile in their thinking and their senseless minds were darkened.
. . . Notice that he doesn’t criticize nonbelievers because they don’t know about God, but ought to. Rather he criticizes them because they do know about God, but pretend to themselves that they don’t. On his account, we are not ignorant of God’s reality at all. Rather we “suppress” it; to translate differently, we “hold it down.” With all our strength we try not to know it, even though we can’t help knowing it; with one part of our minds we do know it, while with another we say “I know no such thing.” From the Biblical point of view, then, the reason it is so difficult to argue with an atheist — as I once was — is that he isn’t being honest with himself. He knows that there is a God; he only tells himself that he doesn’t.