"With Nietzsche's saying that God is dead one arrives at the core of his philosophical endeavors. In Nietzsche's greatest book, Thus Spoke Zarathustra, Zarathustra, who to some extent is the self-idealization of Nietzsche, asserts the death of God near the very beginning of the work. He does not at first prove that God is dead but makes it, as it were, a matter of personal honor that God be dead. The belief in God has become an indecency for all men except those who have had no opportunity to hear of the death of God...Nietzsche's atheism is historical atheism. The saying that God is dead implies that God once existed. God existed while one could believe in God; God is dead because belief in God has become impossible."