I remember a story about a little girl who got mad at her younger brother. She pushed him down, called him a name, and then spat on him. Her father got onto her and said, "Honey, I think the devil made you do that." The little girl answered, "The devil might have made me push him down and call him names, but I thought of spittin' on him all by myself!"
With some of our actions, we wonder why we did them. Paul even struggled with this problem. He said, "For I do not do the good I want, but the evil I do not want is what I do." Then there are the things we know why we did them. We thought them up all by ourselves. As the Psalmist says, "See how they conceive evil, and are pregnant with mischief, and bring forth lies."
This is why Jesus came to be our redeemer. "He it is who gave himself for us that he might redeem us from all iniquity and purify for himself a people of his own who are zealous for good deeds,"