Religion is a fantasy, or fiction, which evolved in various ways over many centuries, with God as the central character. This does not mean that religion is necessarily a bad thing, although often it is. The various holy books of Christianity, Islam, Judaism etc are works of historical fiction. The faith of believers means they have been persuaded that their particular religious fantasy is the one and only Truth.
Atheists know the difference between fantasy and reality.
God exists, but only in human imagination.