Good for you for spending time with your son, and trying your hand with the piano.
As far as church, I don't think it's uncommon for kids this age to begin to doubt. I suspect if you lead through example, he'll come around once he figures things out in his own head, but if you push, it may take years before he accepts the Truth.
M:23 T:26 Me:53, Wife: 60 S:18 D:16 filed 7/16 W moved out 4/28/17