We need to remember that all people are born as sinners (Psalm 51:5; Romans 3:23; 5:12) and that no one is righteous before a holy God (Roman 3:10-11). All people deserve eternal “death” or separation from God forever because of their sin (Romans 6:23; Revelation 20:15). In addition, the only requirement for deliverance from eternal death and condemnation is belief in Jesus (John 3:16-18, 36).
With these truths in mind, what does the Bible say about babies or toddlers who die before they are able to believe in Jesus? Will they go to heaven or hell?
2. God is also love (I John 4:7-8). As a loving Creator He “desires all people to be saved” and has made provision for them through His Son’s death on the cross (I Timothy 2:3-6; cf. John 3:16; 2 Peter 3:9). All people are savable because Christ “gave Himself as a ransom for all” (I Timothy 2:6; cf. I John 2:2).
3. Nowhere in the Bible does it say a person who is not old enough to believe in Jesus will go to hell. Because God is just and gracious (Psalm 9:8; John 1:14-17), He will not punish someone who is incapable of believing in Christ because of a lack of mental development (whether through immaturity or mental impairment).
4. Young children are very valuable to Jesus. They have a special place of love and respect from Jesus. Jesus said, “Take heed that you do not despise one of these little ones, for I say to you that in heaven their angels always see the face of My Father who is in heaven” (Matthew 18:10). Little children are very valuable to God as demonstrated by how close their guardian angels stand to the throne of God. Christ also said, “It is not the will of your Father who is in heaven that one of these little ones should perish” (Matthew 18:14). God the Father does not want any little child to perish forever in hell. In the context (18:6) Jesus is speaking of “little” children who are old enough to believe in Him. We also see Jesus’ concern for little children in Matthew 19:13-15: “Then little children were brought to Him that He might put His hands on them and pray, but the disciples rebuked them. But Jesus said, ‘Let the little children come to Me, and do not forbid them; for of such is the kingdom of heaven.’ And He laid His hands on them and departed from there.” Jesus rebukes those who forbid little children from coming to Him. He says not to forbid little children from coming to Him because “the kingdom of heaven” is occupied by those who possess childlike faith in Jesus.
5. The Bible does seem to teach that a baby who dies in infancy will go to heaven (2 Samuel 12:22-23). In the context of this passage, King David committed adultery with Bathsheba. The prophet Nathan boldly confronts David about his adultery and tells him that the child that Bathsheba has conceived will die. As a result of the confrontation, David confesses his sin, puts on sackcloth and ashes, fasts, and grieves the fact that he will lose his child. When David receives news that the child has died, he quits grieving and fasting and changes his clothing. The prophet Nathan comes to David and asks him why he quit mourning the loss of his son. David replies, “While the child was alive, I fasted and wept; for I said, ‘Who can tell whether the Lord will be gracious to me, that the child may live?’ But now he is dead; why should I fast? Can I bring him back again? I shall go to him, but he shall not return to me.” (2 Sam. 12:22-23). David is confident that the child went to heaven since David says, "I shall go to him, but he shall not return to me"; and other verses indicate that David went to heaven (Psalm 16:10-11; Romans 4:5-8; Hebrews 11:32-33).
Conclusion: While I cannot be dogmatic here, I do believe that infants or toddlers who die before they are old enough to believe in Jesus will go to heaven because:
1. The character of God (holy, just, gracious, merciful, loving) does not allow Him to punish a person for something they cannot do (i.e. believe in Jesus) whether it is because of immaturity or mental impairment (Genesis 18:25; Psalm 7:11; 9:8, 18; John 1:14-17; 3:14-18; I Timothy 2:3-6; Hebrews 4:14-16; I Peter 1:15-17; 2 Peter 3:9; I John 2:2; 4:7-8). No one will question God’s final judgment about the eternal destiny of infants and toddlers because only God is qualified to make this decision!
2. Little children are of special concern to Jesus and He does not want any of these little ones to perish in hell (Matthew 18:1-14; 19:13-15).
3. King David expected to see his dead infant son again in heaven (2 Samuel 2:22-23).
With this said, the number of babies, toddlers, and mentally impaired people from all human history who are "safe" in the arms of Jesus will greatly increase the population of heaven. When considering the infant mortality rate (the number of deaths of infants under one year old per 1,000 live births) which was far greater in the past than the present, it is quite possible that there will be far more people in heaven than in hell.