Have you heard of that madman who lit a lantrin in the bright morning hours, ran into the market place, and cried incessantly, "I seek God! I seek God!" As many of those who do not believe in God were standing around just then, he provoked much laughter...
"Wither is God," he cried. "I shall tell you. We have killed him--you and I. All of us are murderers... God is dead. God remains dead. And we have killed him...
Friedrich Nietzsche, The Gay Science (1882) section 125.
With singing, weeping, laughing, and mumbling do I praise the God who is my God. But what dost thou bring us as a gift?"
When Zarathustra had heard these words, he bowed to the saint and said: "What should I have to give thee! Let me rather hurry hence lest I take aught away from thee!"--And thus they parted from one
another, the old man and Zarathustra, laughing like schoolboys.
When Zarathustra was alone, however, he said to his heart: "Could it be possible! This old saint in the forest hath not yet heard of it, that God is dead!"
Friedrich Nietzsche , Thus Spake Zarathustra (1891) Part 2.
Nietzsche may not have said it, but the characters in his books did.