Some Calvinists today believe that non-elect babies are in hell. Others believe that "covenant children" receive particular favor from God. Still others, such as Charles Spurgeon and Al Mohler, believe that all babies who die are in heaven.
Option 2: God judges children by "the light they had"
Paul said of the Gentiles, "the requirements of the law are written on their hearts, their consciences also bearing witness, and their thoughts now accusing, now even defending them" (Rom. 2:15). God has revealed himself not only to our hearts, but also in our world: "Since the creation of the world God's invisible qualities—his eternal power and divine nature—have been clearly seen, being understood from what has been made, so that men are without excuse" (Rom. 1:20).
It seems logical to extend these assertions to children. They have God's law "written on their hearts" and can see his "invisible qualities" in their world. If they die before hearing (or being able to understand) the gospel, God would then judge them according to their response to what they do know of his word and will. In other words, he judges them by their character and conduct.
This same logic can be extended to the so-called "ignorant," the billions who have never heard the gospel. In this view, God judges them by their response to his law on their hearts and revelation in his creation.
However, Scripture teaches that "it is by grace you have been saved, through faith—and this is not from yourselves, it is the gift of God—not by works, so that no one can boast" (Eph. 2:8-9). Works do not save us, whether they are done before or after we have received the gospel.
In addition, this option would seem to mitigate against evangelism and missions, since children and the "ignorant" could be "saved" through their works. If that is so, missions become unnecessary, and the sacrifices made by missionaries are wasted. In addition, sharing the gospel with obedient children and the "ignorant" risks their salvation since they might reject it and be condemned.
Option 3: God judges them by what they would have done
God is omniscient, knowing all things and all hearts (Acts 15:8). He knew that Abraham would become a "great nation" (Gen. 12:2) and that Pharaoh would reject his word (Ex. 7:4). Jesus knew that Judas would betray him (John 13:26) and that the other disciples would abandon him (Matt. 26:31).
If he knows our future actions, presumably he knows what children who die would have done had they lived. Specifically, he would know whether they would accept or reject his offer of salvation through Christ. If they die before receiving that offer, he would then judge them according to what they would have done if they had lived.
As with the second option, this same logic can be applied to the "ignorant," the billions who have never heard the gospel. However, evangelism and missions become even less relevant since no one needs to hear the gospel in order to be "saved" by its truth.
Option 4: Children who die are with God
My belief is that children who die before they are able to understand and respond to the gospel are with God in heaven. The following assertions have led me to this position.