What about of "Parents in USA" do you not understand from the title of the thread? His parents are already here, so preaching and stirring fear is NOT the answer he's looking for. If you have experience of how you kept your parents busy while there were in the US, please feel freeto share your experience, else shut up.
Going to church to pick up chicks is like a blond guy with blue eye going to Pashupatinath to pick up a Nepali chicks. At least the Church will allow you in, Pashupatinath does not allow anybody in who is not Hindu. Pushy and stubborn believers esp old folks are in every religion.
So if you get, once in a while, some pushy believer, just ignore him/her. Tell him kindly, I'm not interested. That will do it. They will not force a gun on your head. Just rip all the free stuff and the benefits the Church provides and go home. Try to stay away from Catholic and Mormon church, rest should be fine.