@Oylok,
I can't say for other religions, but the christian world is entirely black and white. It's a frightening world of good vs evil, god vs satan. There can be no grey area in such a belief.
The atheist doesn't join with the christian version of good, therefore they must be evil. They don't follow god, so they must follow the devil. They are pitied and scorned, as they have chosen the path of evil.
This arises from the basis of original sin, that there is a knowledge of good and evil running the show.
The truth is the world is not black and white, and the so called knowledge of good and evil is subjective.