Existentialism deals mainly with the concept of the self and its relation to material existence, so not a lot of existentialist literature touches on the intricacies of human relationships. Nevertheless we can infer that since existentialist philosophy tells us that there is no greater meaning or significance to life and so it would seem that your relationship to others would be entirely a matter of personal preference. If you desire friends, seek them out, make yourself happy. If you do not, do not.
That depends on your friends , but most don't care. Its better not to discuss it though religion can be very touchy. People who are religious often have a deep distrust and contempt for atheists due to their religious upbringing. When some friends of long standing realize you're an atheist their attitude toward you can change. Old friends can become distant. An atheist shouldn't keep their Atheism secret but they must always be prepared to be marginalized by those who "believe".
Another Perspective
It doesn't impact friends.
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. Existentialism can be defined as a philosophy that sees human existence in an indifferent universe, as 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.
With that said, your personal atheistic, existential worldview may not impact your friends at all unless you are a member of a group that has people from different backgrounds who enjoy discussing and sharing their world views. Atheists are generally more intellectual than the average deeply religious person. Also, atheists are not as likely to bring up "belief in gods" in conversation as religionists are wont to do. On the other hand, not everyone discusses their religious and personal beliefs. I have many friends, acquaintances, neighbors and business associates who I have known for decades who have no idea that I am an atheist. It simply has never come up. Therefore, it has not impacted them in any way
There are millions of atheists; it is very unlikely they have a consistent view of friendship.
Friendship. a connection between individuals, not as strong as love, but can be close.
What you have described is simply a family that does not believe in gods.
Atheism is NOT A RELIGION. It has no rules. Those are given by morality. Every atheist has different opinions.
Three existential philosophers that were not "Atheist", meaning that they have a lack of belief in a God, or a group of Gods. Getting in to Atheism is a whole different subject that we shall not delve to deeply in just for the sheer fact that different people have their own personal ideas on what it really is -- But, the three philosophers that I found that were NOT Atheist, had a Christianity background. The names of these gentleman are Paul Tillich, Gabriel Marcel, and John Macquarrie. Given that these gentleman professed Christian faith, doesn't mean that any other known Existential Philosophers were not Atheist. There are other religions and beliefs that many held dear, but once again.
It was probably Lewis's friendship with JRR Tolkien that caused his conversion.
because there is nothing but yourself
Sensory input refers to what you see, hear, taste, touch and smell. Anything else is supernatural and therefore only in the mind of the beholder. The human brain is built to play tricks on its' owner.
Jean-Paul Sartre.
Being an atheist does not mean that you don't have the same feelings of love, hate or indifference that are experienced by those that are not. these emotions are built into every human being and they are what help the human race survive against even their own evil intentions.
That the human being is supreme, period
Martin Heidegger (1889-1976). Another answer is Nietzsche. This is the most often existentialist philosopher named as an influence on Hitler.
The atheist existential view of ethics is that ethics do not emerge from supernatural sources but from pragmatic sources; a good system of ethics is one that contributes to the healthy functioning of the society which adopts it. In other words, we are ethical because it is useful to be ethical, not because God commands us to do so.
An English atheist is an atheist from England.