I have heard this debate when I was a child. After many years and coming to Jesus Christ, and becoming a child of God I often thought about this debate. With the wisdom I have acquired I want to answer the question, if God places a baby in hell.
The scriptures say that you must be born again to attain internal life. They say you must be baptised by both water and the spirit. The scriptures say that you must have asked Jesus Christ to be your lord and saviour in order to go to heaven. Does this mean that a baby who is ignorant, and doesn’t even understand human speech will be placed in hell? I do not think so.
God is not bound by rules, laws, or beliefs. He is not bound by morals or ideas. God is above the law, and God is good. It would be evil for God to place the ignorant baby into hell. But God is not evil. God can do what ever he desires to do, and takes no pleasure in any man's death. God's judgements are righteous and just.
God is able to take the spirit of the baby, and put that spirit into a new body, in heaven. In heaven that baby will be raised up by foster parents, who raise the baby up in God's word, by God's standards, and in heaven. If that baby who grows up into a man, then rebels against God, then that baby could be in enough trouble to be cast out of heaven. But because the baby is in heaven, and not attacked by the demons that the people of the earth are attacked by, then I do not think the baby would rebel.
Satan wants the people of the earth to rebel against God. This lie about God placing babies into hell is a way for him to steal from you. After he has stolen God from you, he will then kill you. What this results in is you being destroyed. The devil only comes to steal, kill, and destroy. Rebel against Satan, not God.