According to Sartre, existentialists believe that we are all forced to sit for the final exam, “What does it mean to be a human being?” We answer this parent question of life in the ink of our choices and actions. Now, Kierkegaard, Gabriel Marcel, Miguel de Unamuno y Jugo, and other non-atheist existentialists would disagree with Sartre’s claim that there is no underlying plan in our lives, but all the existentialists concur that it is through our choices that we become who we are.
Basic writings of existentialism, Gordon Marino