Atheistic existentialism is also known as secular existentialism, naturalistic existantialism, materialistic existentialism, humanistic existentialism, and Sartrean existentialism. Friedrich Nietzche and Jean-Paul Sartre were the main atheistic existentialists. Some of the features associated with atheistic existentialism include: Being in-itself is an object that is not free and cannot change its essence. Being for-itself is free; it does not need to be what it is and can change. Consciousness is usually considered being for-itself.