The typical atheist rebels against God as a teenager rebels against his parents. When his own desires or standards are not fulfilled in the way that he sees fit, he, in revolt, storms out of the house in denial of the Word of God and in scrutiny of a great deal of those who stand by the Word of God. The epithet 'Heavenly Father' is a grand reflection, a relation to that of human nature.
Of all the major religions, or lack thereof, the atheist's is one of the best pretenders: his foundation for all existences, as well as moral behaviors for the permanent good of mankind, begins at science but ends at himself, the Napoleon complex of both intelligence and imagination. On the other hand the anti-theist wouldn't survive without a deity beyond himself to hunt. He doesn't pretend, he simply nullifies his own position.
Man has 2 common problems with God: the one is that there is evil in the world; the other is that free will is limited. The one, he is charging that the world is too evil; the other is that it is not evil enough.