All Existentialists are not created equal,in my humble opinion. Although there are defining characteristics that go along with the movement, there is also a dividing line amongst Existentialist philosophers. For example, Sartre is concerned with acting, Heidegger is concerned with knowing. Kierkegaard aligns with faith and Nietzsche says "God is dead".
Just pointing out, that its quite difficult to fully define.
It seems like post WWII, it divided into two branches, humanism and Christianity. Is this accurate?
I am fascinated by Existentialism, I believe human knowledge is limited and fallible. and I also believe that one can be deeply committed to truth and investigation and simply fail to find adequate truth. I will post more as I delve more into this.