The Bible is does not address this question directly, but it does talk about the innocence of children. The age of awareness is when we have the ability to distinguish good from evil. In Deuteronomy 1:39 we read that the children were allowed to enter the Promised Land. The adults that had not trusted God did not get to enter. Young children have not rejected God’s revelation as they aren’t aware of it. Hence, one who has not rejected the Word of God will be saved. God who is merciful and loving can be trusted to do what is right, just and fair.
Jesus blessed ‘little children’. He even said, “Such is the Kingdom of Heaven.” He certainly would never bless someone going to hell. The root question is, does God treat willful knowledgeable disobedient sin differently from our inherited sin nature from Adam? We don’t know.
Jesus said, ”I Am the Way, the Truth and the Life. No one comes to the Father but through ME.” (John 14:6) All [which would include children ] have sinned and come short of the Glory of God. (Romans 3:23)
When a child reaches the age of accountability (i.e. the age of innocence is over, which varies for each one), then they are aware of their need for a savior. Children as young as 4 or 5 have been known to pray to invite Jesus into their lives and receive the assurance that they have heaven as their eternal destination.
While we don’t know when a child becomes accountable for their sin nature, we do know that sooner or later each has to come to terms with his or her sin. That’s why we encourage all to trust a loving and merciful God to judge fairly the ‘little children’. And, we can all point young ones to God and show them what it means to become a true child of God. Check out our post: How does one become a Christian?