I think I would need more info was he a part of the PCA or PCUSA church they are both presbyterians but differ in a lot of ways. The guy who posted look at the Westminister confession of faith is right basically that is supposed to be their core beliefs, but it is difficult to says how closely his church stuck to these precepts unless I have a more specific church background. Oh by the way I am a member of the PCA church.
Basics would be the five points of calvinism and the five sola’s
TULIP: Total depravity, Unconditional election, Limited atonement, Irresistible grace, Preservence of the saint
Sola scriptura, Sola gratia, Sola deo gloria, Sola christo, Sola fide
I do not think that these will be points of agreement though, but are a good read if you like studying religion. You are really gonna have to work hard deppending on how much he went to church before and actually listened, because the hard part is rearranging how someone groups and interprets verses. My friend swicthed to the RCC I will ask him for some help