god is dead - friedrich nietzsche
Nietzsche was probably saying that the concept of god was dead, or that it's death was inevitable. At the time atheist philosophy and anti-theist philosophy was becoming more popular. Also, when he says "god is dead" he is also saying that absolutes were dieing. An epistemological skeptic, Nietzsche criticized science and its method of acquiring "proof." He also attacked that moralities of that time which were what he termed, "master-slave" moralities. In that sense, the absolutes formed within morality, such as altruism, were dead.
Nietzsche probably wasn't at all trying to make a comment on God's existence. The madman had more of a warning/pseudo-lament feel to what he said.