Postmodernism's view of psychology is that of the socially constructed self. Man is born a blank slate and his environment molds him into the person that he becomes. If he is raised in an upper-middle class suburban American home, given an above average education, and encouraged by his teachers and parents to follow his dreams he might easily become the next president of the United States. Conversely, if he is raised on the south side of Chicago where violence and drug abuse are a prevalent everyday occurrence it is far more likely that he will end up in prison before his teen years expire.
The implications of this view of psychology are enormous and devastating. If man is simply the product of his surroundings then he is no longer responsible for his actions and everything he does is justified in light of the society he grew up in. With his environment conveniently available on which to lay the blame for his actions he can now get away with nearly anything.
When God is taken out of a worldview's picture that worldview must compensate and find a cause for the evils and beauties of the world. Man's actions can no longer be blamed on his inherent depravity and desperate need for God because God no longer exists. Now man is the result of his circumstances, whether good or evil. He answers to no one, and can justify his every action without being questioned. I don't think it necessary to describe the result of this twisted view; we see it all around us.