By "damaging" I mean -- learning something that will be hard to unlearn. Religious themes are present in many many places, fairytales, poems for small children, etc. I don't want to censor them because that would make my children's life poorer. It's easy to balance the violence from fairytales (cutting through wolve's insides?) but when it comes to religion - there's not enough counterbalance in my opinion. There are no "Scientific fairytales for small children" that I've heard of (I'm sometimes thinking of writing such thing but am not good enough in writing; I would love to see people that have "light pens" like Dawkins and specialists from other fields writing a book of short "fairytales" that would have some kind of scientific background; think of Lem's "robot fairytales" kind). Such book would try to "smuggle" a bit of scientific consiousness at a pretext of a fun story -- exactly how religion puts its roots in young minds.
But maybe I'm overthinking stuff. Both me and my wife are atheists and it will be different with my kids than it was with me. I grew up among believers and used to strongly believe in god, too. I never suffered too much because of it or because I stopped believing at one point, but from today's perspective I can see that this religious belief did took away some of things from my youth. I'd love to spare my daughter from this but maybe I cannot or it will Just Work