In Mark 10:14-15 Jesus said, 'Let the little children come to Me, and do not forbid them; for of such is the kingdom of God. Assuredly, I say to you, whoever does not receive the kingdom of God as a little child will by no means enter it.' Clearly Jesus was using children as an analogy, saying that to enter the kingdom a person must have childlike faith. This is not a promise that the kingdom belongs to all children.
In the answer you are referring to, we did not mention anything about children going to hell. Please answer these questions and then we will respond to your answers:
1. Why would God favor a child simply because His parents are believers. The child has nothing to do with that. Are you saying that the children of the unsaved go to hell?
2. If the child of a believer is saved, does this mean that at some point in his life he becomes unsaved and must then be re-saved? How does a child suddenly become unsaved?