The issue isn't religion. Not really. It's boundaries. Unless a kid is being legitimately abused, other parents have no right to intervene in how that kid is being raised. And, no, being raised as an atheist isn't abuse. Everything else is a side show. A particularly vile one, since it's people trying to induct other people's children in their cult through deceit and peer pressure, but a side show nonetheless. Nothing about this situation is okay.
"I was thirsty for everything, but blood wasn't my style" - Live, "Voodoo Lady"