Christianity beleives that there is but one "correct" God out of the thousands that mankind has worshipped; Atheists believe that there is one less than that.
While no comments can be applicable to an entire group, the following points about the level of lifestyle and interactions with other people of :Atheists: and "Christians":
Opinion
You have asked a complicated question that crosses several areas of discourse. Briefly:
Existentialism is difficult to explain as it takes on different forms for different people but for most of its followers, it can be described as atheistic although nineteenth century philosophers discussed the existence and non-existence of god. Existentialism can be defined as a philosophy that sees human existence in an indifferent universe, unexplainable, that we have freedom of choice and are responsible for our own acts: each person's experience is as a unique individual rather than a member of a collective. There is no ultimate purpose. There is no created meaning (or purpose) for life and humans can create their own meaning.
Atheism is the absence of belief in gods. Atheistic existentialism formally excludes religious belief from philosophical existentialist thought.
Alternatively, Christianity is a religion based on the life and teachings of Jesus who is worshipped as the son of God and who, they believe, controls human destiny. Christian beliefs vary widely however, all have a strict set of doctrines and focus on the next life perceiving this life as a time for penitence, prayer and preparation for the hereafter.
That life exists.
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.
Atheists believe friends exist.
Families of atheists exist.
We are pretty sure it exists.
Friedrich Nietzsche - 1844 - 1900
As far as I am concerned existentialism plays no part.
I am not sure what is meant by Life Domain Family. It may not necessarily have to do with atheism. and nothing with existentialism.
Humans have values, secularly as well as religious. Religion need not play a part in human values. Existentialism is moot.
Suffering and dying exist. Existentialism has no part in atheism.
Sexuality exists, just like new, fun big words!