I might argue that if your GF's parents don't show you any respect it's even better to ask the father in law. At least you will forever know that you were the bigger person in the relationship and that you gave them a chance to "have a seat at the table." How is your relationship with them now that it's been a while and you gave them a granddaughter?But there's a world of difference between doing that and actually giving a shit what they say.
Agreed, that's why I put this in there: Everyone involved knows that really this is going to go down no matter what, but it gives the parents a seat at the table.
-Unless the parents are complete morons, they know it's a formality and that their daughter is getting married one way or the other. It can be a nice place for both the son in law and father in law to state what is and is not important to them. Religion wasn't very important to me and I let him know that while I was "spiritual" I wasn't "religious" and wasn't going to be.