Sin

Sin is a religious term for evil deeds committed by conscious beings.

Unlike the humanist concept of evil, sin is defined entirely in terms of doing things which God specifically prohibits.

Counter-apologetics

Since atheists do not believe in God, it is meaningless to accuse an atheist of being a sinner (or to threaten them with the purported consequences of being a sinner). Humanistic atheists recognize the concept of right and wrong actions in terms of their impact on other people, but the idea of sin is basically irrelevant without appealing to a deity.