I think it depends on the church. I wouldn't usually have a problem with it, if it were my child. But some of these churches can be harsh. I had a cousin who went with a friend to Sunday School one day, and the teacher found out my cousin was a different religion. So she gave a "lesson" on how people of other faiths are going to hell.
I love to learn about other religions and my children will be raised with the knowledge to choose for themselves, but no one should EVER be told that they are going to hell because of their beliefs/faith. That is so wrong. On so many levels.