Friedrich Nietzsche writes his famous declaration, God is dead several times throughout his works.

The meaning of the phrase is often misunderstood — many have interpereted that Nietzsche believed in a literal death or end of God. Instead, the line points to the western world’s reliance on religion as a moral compass and source of meaning. As he explains in The Gay Science (Section 125, The Madman):

“God is dead. God remains dead. And we have killed him. How shall we comfort ourselves, the murderers of all murderers? What was holiest and mightiest of all that the world has yet owned has bled to death under our knives: who will wipe this blood off us? What water is there for us to clean ourselves? What festivals of atonement, what sacred games shall we have to invent? Is not the greatness of this deed too great for us? Must we ourselves not become gods simply to appear worthy of it?”

Nietzsche’s works express a fear that the decline of religion, the rise of atheism, and the abscense of a higher moral authority would plunge the world into chaos. The western world had depended on the rule of God for thousands of years — it gave order to society and meaning to life. Without it, Nietzsche writes, society will move into an age of nihilism. Although Nietzsche may have been considered a nihilist by definition, he was critical of it and warned that accepting nihilism would be dangerous.

Nietzsche’s statement prompted several replies from his more religious opponents, and from later existentialists. Albert Camus, for example, considered the human need for higher order absurd. He argued that the “death” of God was inconsequential—that humanity had no need of a higher authority or the threat of divine wrath to live a good and moral life. Some other philosophers were less prepared to part with the concept of higher authority and instead tried to imagine an absolute morality that didn’t depend on a supreme being.

The following are a list of occurences of the "god is dead" statement in Nietzsche's work:

The Gay Science (Sections 108, 125 and 343)

Thus Spoke Zarathustra (Prologue and XXV)