Sometimes, in Christian theology, it's used to describe someone involved in the Christ's death and used as an excuse for antisemitism. It's also sometimes proclaimed of Nietzsche by some of his less tempered followers. Myself, frankly what comes to mind is the line from the English dub of Princess Mononoke, "He's a god, you fool. It'll take more than one shot." -- the context being a Shinto kami. In any case, this is something of a big thing, even in non-monotheistic contexts. Adopted in 1577 from Medieval Latin deicīda, from Latin dei- (combining form of deus, god) + -cīda, killing.
I'm not going to punch out Cthulhu -- this calls for deicide.
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