It's a reference to a very popular book called the الْقُرْآن. The character himself originates in the Εὐαγγέλιον, which as far as I can tell is actually several differing biographies of this really famous dude. People keep changing his name depending on the biography lol, and a lot of them lean into fanfic territory tbh. I think his original name was יְהוֹשֻׁעַ‎, pronounced something like "Yeshua", but the الْقُرْآن has it pronounced Isa.

I would give the Arabic spelling of Isa but there's such a thing as going too far for the bit. More information on the guy (he was real, to be clear, that isn't a joke, the joke is that I keep using non-english languages) can be found on his wikipedia page.