We believe atheist families exist all over the world. Existentialism has no part.

Most atheists I know are not into philosophy, except empiricism.

There is no impact. If people don't like people of a different sexuality, it's because that's just how they think, not because they're atheist.

There isn't an atheist book about what you should think about heteros/homos/trannys etc.

The two main types of Existentialism are Christian Existentialism, which integrates religious beliefs with existential ideas, and Atheistic Existentialism, which rejects the concept of a higher power or divine order in favor of individual freedom and responsibility.

Atheists have friends like anyone else; existentialism is irrelevant.