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.

It does no such thing ! You may want to read about philosophy to learn what existentialism is.

Existentialist epistemology is, like most existentialism, based on personal choice - i.e. a choice to believe.

Ernest Breisach has written:

'Introduction to modern existentialism. --' -- subject(s): Existentialism