I went to a private Catholic school in a developing country (a very religious country). They never mixed religion in science classes! During evolution topic, we even asked our science teacher about evolution vs creationism. She just said she is religious but also believes in evolution and left it at that. None of our science textbooks has any religious hints on it! We were taught about reproduction and puberty stuff in 4th-5th grade. We have discussions about LGBT in my religion class and share our opinion on it, my religion class teacher never dictated what we should believe in. This was 10+ years ago. I now live in America and an atheist lol.

The comments make it seem like they are all bad!! But it's not really. It depends on the school and the teachers, OP's son just went to a bad one unfortunately.