Well damn... Prepare a part before church and do the rest after. There are indeed some churches here that have sermons for hours, but thank God the one we went as a family doesn't do that.
We would usually also buy one meal at the church (every Sunday another sister prepares a dish to sell as a means to raise money for the church) to keep us good and then my mother could take her time preparing our dinner.
Oh, and I think some families in USA also make a big deal out of Sunday dinner. There's a movie about it. Can't remember the title though.