Say a child knows about hell from discussions with friends, or attending a church ceremony (with friends, family or otherwise), or seeing a billboard commenting on it. If, in this case, the child is brought up in a Christian home, and is thus told:
1) This is what hell is like .... (own definition)
2) a. We are all sinners, and we all deserve hell, BUT (go to number 3)
b. All you have to do is be a good person and follow a few rules about being a good person
3) a. Say that if you believe that Jesus died for your sins, and you have faith, you will not suffer after this life, no matter what you do. (Just repent)
b. Discuss the rules and why they make sense in a pragmatic way. (It would be hard to slam the 10 commandments and parables of Jesus.)
4. Mentioning that heaven is also a likely possibility, and that it's the child's choice.
None of these options seem abusive to me. Even if a parent coerces their child to have faith in Jesus, the parent is thinking that they are saving their child, not harming them. If it is used as truly abusive, and the parent does something like this:
1) Tell the child about the kinds of suffering in hell, complete with explicit hellfire and suffering
2) Tell the child they are going there because they are a piece of ****
3) Tell the child that anything wrong they do will send them to hell
4) Threatening the child with hell constantly, or condemning them to hell.
It does not seem to be a reasonable way to handle it. THIS is a form of abuse. Not the former, because I believe in good intentions, and I think the parents in the first examples merely want to take care of their children in this life and after. Why is that abusive?