I need help and this situation is keeping me up at night.

As soon as I told them, they said they were going to name my baby after a passed relative. They also said we have to marry with only the parents attending  and that I have to start attending their church. I am Mormon not catholic. They said they're going to look after it while I'm working which I am grateful for. But I'm not sure. This is the first grandchild on both sides and I can already see our families dividing. I want to keep both grandparents happy but I will say what I need too because this is our first born. 

Can someone help me, it's really stressing me out ?