What else is the appropriate approach? The bible has its answer, but people argue that the bible may be wrong, at least no one can proof its correctness.
你能证明谁在天堂里谁在地狱里吗? No, I can't. I don't think anyone is able to do that. I can only confess my personal faith in Jesus, who has died for my sin, and has resurrected for my rightousness. You don't want me to lie, right?
Getting back to 老一的 theme,"信了God,就杀死了包括自己的7个孩子在内的8个孩子", my opinion is that the person is just crazy, 精神病. It is fine if you have a different conclusion. People with difference opinions can live together happily and peacefully. Let's not say: I am right, you are wrong; OR you are right, I am wrong.