Atheism is a lack of belief in any god; no more, no less. Morals can be driven by a desire to do good in the world. Goading people into doing good deeds by threat of eternal suffering is boorish.

Abstaining from murder allows survival by forming alliances. Also:

In stark contrast, organized religions have justified murder, torture, genocide, infanticide, and slavery. If anything, propensity towards violence increases in proportion to the fundamentalism of a person's religious faith.