No one will go to Hell because they have never heard of Jesus. People go to Hell because the sin in their life separates them from God. Similarly, people do not die because they have never heard of the cure for a disease. They die from the causative agents of the disease, such as a virus, or bacteria, some trauma to the body, or a genetic defect. This is not an attempt to be evasive or facetious—the distinction is critical to understanding this issue. In the case of spiritual death the causative agent is sin. Is there a cure? Yes, God has already made it available, completely free to each individual, through the substitutionary and atoning death of Jesus Christ, and our embracing that cure through a confession of faith.
What about those who have no opportunity to hear of the cure? There are two important points that are relevant to them. One, God says through the writer of Hebrews that “He rewards those who seek Him” (Hebrews 11:6b). God knows the seeking heart which is not content with worshipping stones, ancestors, false gods or nothing. He is not locked out of the universe He created, so He can guide the seeker to a source of the Gospel cure, or bring a messenger of that cure to the seeker. He can even reveal Himself to them in unusual ways to satisfy their spiritually hungry heart. This is not theoretical—it is the actual testimony of many who have been there.
Second, there is a tremendous burden upon each person to realize that their personal sin is not always a private issue. The drunk who crosses into oncoming traffic with his car and kills a family of four is no longer sinning privately. And the four who were killed—did they deserve such a fate? Likewise, when a father or mother chooses to live without God, their children often grow up without the opportunity to know God. If that particular father was the founder of a tribe of people, each member of the tribe in a sense becomes a victim of the father’s sin. God respects our wills and honors our choices, even when the consequences impact others temporally and even eternally.
Because all people in the world today are derived from Noah and his family (who knew and trusted God) then it follows that somewhere along the genealogies since then, there were some who broke the chain of faith through their sin—and ignorance and deception concerning God was the result for their descendents. They are lost because of sin—whether no one has told them about the cure or they have denied it. That’s why Jesus was so insistent and passionate about His command that “…repentance for forgiveness of sins would be proclaimed in His name to all the nations…” (Luke 24:47). He wept over lost Jerusalem (Luke 19:41-44) and said He came to seek and to save the lost in the world (Luke 19:10). We who have experienced the cure need to shout the Good News to others from the housetops!
The worst thing you can do if you are truly concerned about those who are outside the influence of the Christian faith (i.e. those who have never heard) is for yourself to remain outside. You aren’t helping by being critical of the problem or denying that a problem exists. Help proclaim the cure!
Children, the mentally challenged, etc. are considered by most Christians to be special cases, and not to be destined for Hell. For more insight on this and other relevant questions, see the following books: John Sanders, ed., What About Those Who Have Never Heard? (Downers Grove: InterVarsity Press, 1995); Lee Strobel, The Case for Faith (Grand Rapids: Zondervan Publishing, 2000), pp. 145-167 and 223-245.