My FI is agnostic. I'm atheist or agnostic, depending on my mood., but raised Catholic. We are having a Catholic wedding, as I consider myself culturally Catholic and the tradition of a church wedding is important to me.
My FMIL is born-again Christian. She HATES that we are having a Catholic wedding, to the extent that she tried to forbid it. She also doesn't like me, but whatever.
FMIL says that she will drop the fight against a Catholic wedding as long as FI and I go talk to her priest. I assume he's going to do his best to get us to accept Jesus Christ as our lord and savior. Not gonna happen.

In order to make FMIL happy, I have to play nice and pretend like I don't think that believing the dinosaurs were on Noah's ark is absolutely psychotic.
Did I mention that we are spending the whole Thanksgiving holiday with them? Oh, and she wants us to surprise her side of the family with the announcement. They all think I'm a terrible person.
Kill me. Please.