My wife is Catholic, I am not. My kids attended the Catholic Church quite regularly (as did I as their father) and I had no problem exposing them to their teachings. They all attended so called catechism classes and participated in their first communion. They were a little confused on why Dad (me) didn't accept communion but after a while they understood (non-Catholics don't participate in communion unlike say Episcopalians). My oldest at about the age of nine had a traumatic experience. During the new school year (and new year of catechism classes) after about the third week his catechism teacher died. She was about 10 years younger than my wife and I (early 30s) and her aorta burst, due to an aneurysm, in her sleep one night causing her to die from internal bleeding. It was totally unexpected. Anyway, I took him to his first visitation just to offer condolences to her son (who was in his class) - it was his first experience with death. That was a Friday night. I watched him closely and the experienced didn't seem to trouble him that night or Saturday. Then on Sunday when we were getting ready to attend Church/mass, my wife kind of got on his case (my boys and I always tend to run late which infuriates her) and he came to me and promptly said he won't be attending. He obviously struggled with the proverbial question of "why do bad things happen to good people" issue. In his eyes here was the perfect Christian, a loving mother and teacher and she was struck dead for no apparent reason in his eyes. Why would a loving God let that happen? He didn't quite use these words but in nine year-old language essentially told me "it's (Christian religion) all a crock of shit." All I could really say is I didn't quite understand it either. He was the typical first born - always trying to please his parents, not a rebellious bone in his body, a favorite of adults (teachers, Scout leaders, coaches, etc.).
He's in his mid 30s now and a very grounded, compassionate, kind, charitable, moral, loving kid but at this stage in his life, he's about as far away from believing in God/Christ as one can be. I'm at peace with that.