The gospel of Jesus Christ is good news. It is not merely good news for the few who came to know Christ before they die. It is good news for the whole of creation—even for all those who died before they ever heard of Christ.
Jesus Christ is the atoning sacrifice not merely for the sins of Christians but for the sins of the whole world (1 John 2:2). The Creator is also the Redeemer of his creation (Colossians 1:15-20). Whether people know that truth before they die is not the thing that determines whether it is true. It depends entirely on Jesus Christ, not on human action or human response of any kind.
Jesus said, "For God so loved the world that he gave his only Son, so that everyone who believes in him may not perish but may have eternal life" (John 3:16, New Revised Standard Version throughout). It is God who loved the world and God who gave his Son, and he gave him to save what he loved—the world. Whoever believes in the Son whom God sent will enter into eternal life (better translated "the life of the age to come").
The verse says nothing about that belief having to come prior to physical death. In fact, it says that believers will not perish, and since even believers die, it should be obvious that "perish" and "die" are not the same thing. Belief keeps people from perishing, but it does not keep them from dying.
The kind of perishing that Jesus is talking about here, translated from the Greek word apoletai, is a spiritual death, not a physical one. It has to do with utter destruction, with being abolished, put an end to, or ruined. Those who believe in Jesus will not come to such a final end, but will, instead, enter into the life (zoe) of the age to come (aeonion).
Some enter into the life of the age to come, or kingdom life, while they still live and walk on the earth, but in the grand scheme of things, this happens to only a few of those who make up the "world" or "kosmos" that God loves so much that he sent his Son to save it. What about the rest? This verse does not say that God cannot or won’t bring to faith any of those who die physically before believing.
The idea that physical death is a barrier to God’s ability to save, or to his ability to bring a person to faith in Christ, is a human interpretation; the Bible states no such thing. We are told that everyone dies, and then they are judged (Hebrews 9:27). But let us remember that their Judge, thank God, is none other than Jesus, the slaughtered Lamb of God who died for their sins—and that changes everything.
