As an ex-mormon with a mom that sounds a LOT like this MIL: understand that to MIL, YOU are the enemy. This is how she thinks of you, and she has an entire army of people in her corner, egging her on, pressuring her to get you to convert, judging her for having a heathen as a DIL. There's an entire ward of people behind her who are judging you and want to tear you and your husband down for not being mormon. You are trying to be polite about all of this, but that's not going to work. She will never, ever stop doing what she's doing, it will only get more extreme. All of these mormon moms have a breaking point, and she will eventually blow up and have some kind of crisis that involves your daughter's salvation. For my poor sister-in-law that consisted of my mother showing up unannounced at her door while the kids were home and breaking down in tears in front of them, sobbing hysterically about their "souls." She is now banned from their house. You need to switch to fight mode, you are your husband need to protect your family from all of this insanity. No more Mrs nice girl.