It is not often that we get to see a living example of a complete and total rejection of God. Most atheists are inconsistent and do not push their anti-theism to its logical limits. Some do not think clearly enough about their own project to bring it to completion, while others do not have the courage to walk the path of anti-theism to its end. Of course, we will see the true results of God-rejection vividly on the day of God's final judgment, but in this life it is rather uncommon.
However, there was one man in Germany in the nineteenth century who was both diabolically brilliant enough and savagely courageous enough to accept the full implications of atheism. His name was Friedrich Nietzsche. I was reminded of this as I recently read 10 Books that Screwed Up the World by Benjamin Wiker. If you are not familiar with the history of Western thought, I would recommend Wiker's book as an easy introduction to some of the worst stuff to have come from the mind of man in the last 500 years (if you can stomach it). Note what Wiker observes about Nietzsche.
Nietzsche completed the modern rejection of God that began with Machiavelli. He made clear to those who swallowed his words what the real implications of godlessness were - a world without good and evil, a world ruled by the will to power. Already in 1884 strange megalomaniacal utterances were finding their way into his letters and books. In his letters he spoke of striking "a destructive blow against Christianity," launching the "greatest decisive war in history" where "we shall have convulsions on the earth such as have never been," announcing that "the old god is abolished, and that I myself will henceforth rule the world," and signing himself "Nietzsche Ceasar," "The Anti-Christian Friedrich Nietzsche," or more tersely, "The Antichrist." In 1885, amidst such revelries, Neitzsche would begin Beyond Good and Evil, publishing it in the following year. Der AntiChrist was written in 1888 but not published until 1894.
Nietzsche's complete dedication to drinking to the bitterest dregs the full depths of atheism ended in his own drop into the depths of insanity in January 1889, only four months after writing Der AntiChrist. The last decade of his life was spent in the darkest corners of madness, deteriorating in every way, at one stretch keeping everyone in the house awake repeating like a hideous drum, "I am dead because I am stupid...I am stupid because I am dead."
It is not by accident that the Scripture says, "The fool says in his heart, 'There is no God'" (Psalm 14:1; 53:1; cf. Rom 3:10-18).