Simply put man is but a mere insect in the grand sceme of the universe. Its a big universe guys, and its naive to think that anything that we do will have any lasting impact. I don't believe in morality. I don't believe in the existence of good or evil, or in the existence of the immortal soul. When I use those terms, I use them because they have a given meaning to everyone and can help explain a concept, not because they exist in a metaphysical state.
Man is controlled by the urge for self-preservation.
His every action is that so he can keep on surviviving. He therefor never makes any choice between good and evil, as he will always approach what he sees best for himself. Because man has these unconquerable drives he does not truly have free will. His fate is dictaited by his drive for survival, and nothing else. Reason is established only to help satisfy that need for survival.