For the existentialist it was man's feelings and passion which made him a man. Feelings are the standard for truth. It is true if I feel strongly about it. Like all humanist philosophies existentialism contains within itself the seeds of its own destruction. The number one critique of existentialist philosophy is the inconsistency with which they live their lives.
Current existentialists are likewise advocates of causes.
Sartre himself seemed to admit this near his death. B. Existentialism is opposed to rationalism yet they write very rational books using all the laws of logic to convince readers that irrationalism is the way to meaning. From the OT book of Judges we know the answer. D. Existentialists deny any absolutes exist yet they treat human subjectivity and freedom as absolutes. We may appreciate its artistry, but the basic philosophy of this movie is existentialism, and it is this total rebellion against any transcendent values which give us the violence we see today in art and society.