Atheist Richard Dawkins:

Preaches the atheistic anti-life dogma that works AGAINST natural selection by causing in atheists an aversion to reproducing their genes (out of three marriages Dawkins could only stomach the creation of one child), and/or killing their offspring by the millions every year.

The Barna Research Group found regarding atheism and the morality that those who hold to the world views of atheism or agnosticism in America were more likely, than theists in America, to look upon the following behaviours as morally acceptable:

illegal drug use;

excessive drinking;

sexual relationships outside of marriage;

abortion;

cohabiting with someone of opposite sex outside of marriage;

obscene language;

gambling;

pornography and obscene sexual behaviour; and

engaging in homosexuality and bisexuality

Given the many diseases associated with sexual promiscuity, the Bible’s prohibition against sex outside of a monogamist, long term marriage is quite arguably one of the many examples where the Bible exhibited knowledge that was ahead of its time.

Dr. Phil Fernandes states the following regarding atheism and moral relativism:
“ Nietzsche preached that a group of "supermen" must arise with the courage to create their own values through their "will to power." Nietzsche rejected the "soft" values of Christianity (brotherly love, turning the other cheek, charity, compassion, etc.); he felt they hindered man's creativity and potential....

Many other atheists agree with Nietzsche concerning moral relativism. British philosopher Bertrand Russel (1872-1970) once wrote, "Outside human desires there is no moral standard."

A. J. Ayer believed that moral commands did not result from any objective standard above man. Instead, Ayer stated that moral commands merely express one's subjective feelings. When one says that murder is wrong, one is merely saying that he or she feels that murder is wrong.

Jean-Paul Sartre, a French existentialist, believed that there is no objective meaning to life. Therefore, according to Sartre, man must create his own values.

There are many different ways that moral relativists attempt to determine what action should be taken. Hedonism is probably the most extreme. It declares that whatever brings the most pleasure is right. In other words, if it feels good, do it.
One's conscience becomes the sole arbiter between right and wrong. Good luck with that.