Im 14 and i dont believe in god but my boyfriends dad invited me to church with them what do i do?

my boyfriends dad is very religious but this is one of the best ways to impress him even Tho im 14 i plan to be with this boy for a very long time it seems stupid but he has even proposed to me and if this man is going to be my future father in law i have to make a good impression but what should i do tell his dad no i don't believe in Kdo go along with the charade