It is because evolutionists deny the very existence of the Creator. When the Creator is not known, God is not known. When there is no known God, there is no idea of heaven and hell. In fact, the very idea of any future life is lost. The result is that there are no rules for moral conduct.
Human beings become no more than animals.
In fact, they become worse than animals, for animals have a blind instinct, from God, to act properly. God directs man by commands, not instincts. Before condemning evolutionists, it is only fair to hear from their own mouths exactly what they teach. In order not to violate the copyright rules it is necessary to paraphrase the article. A Harvard Professor of evolutionism, Stephen Jay Gould, proposed to a group of educators, at a symposium, that they should not panic over creationism, which he labels as an American bizarrity.