Yeah, assuming Sherry just stated her opinion and didn't force anything, Spencer and his mom both need to grow the fuck up. Not everyone agrees with them, and they have to learn to live with that. So long as she isn't trying to deconvert him, there should be no problem here. She's not overstepping her bounds.
If her sister thinks that merely stating her opinion when asked is an act of "trying to corrupt her child", she should take a long, hard look at her religious beliefs and how fragile she feels they really are.
If her sister thinks that merely stating her opinion when asked is an act of "trying to corrupt her child", she should take a long, hard look at her religious beliefs and how fragile she feels they really are.