Why so many Christian acronyms?

Indeed, it’s hardly a Christian thing. You can find a bazillion people who will tell you that “Fuck” is an acronym for “For Unlawful Carnal Knowledge” or some such thing, or that “golf” means “Gentlemen Only, Ladies Forbidden.” A teacher once assured us that the rock band Kiss was derived from “Knights In Satan’s Service,” as apparently service to Satan requires writing popular music. All these are of course the most ludicrous nonsense.

I grew up attending church regularly and even attended a private Christian elementary school, yet I’ve never seen or heard anything like what the OP is describing.

I do recall seeing one of two lame puns (e.g. Sonshine), but no backronyms.

How is that not a Christain thing though? it was Christian groups that came up with Knights In Satan’s Service (KISS) or Anti Christ/Devil’s Child (AC/DC) as a way to condemn the bands for being devil worshippers.

E.V.I.L.: Every Villain Is Lemons.

Yes. Though they may also be used in adult sermons for the same reason. I’ve never heard anyone claim that these are how the words were formed, or that this is literally what they mean.

It’s just a way to encapsulate a teaching in an easily remembered way. You get Christian joy by putting Jesus first, Others second, and Yourself last. Faith means trusting God.

As for why they are popular in Christianity (for certain values of popular)? Because mnemonics work in a religion for the masses. Just like Roy G Biv or My Dear Aunt Sally.