What will happen to the people who have died without hearing of Jesus Christ, the gospel, nor had the opportunity to accept Jesus Christ?
Our God has always communicated compellingly unmistakable messages for salvation. Salvation requires faith, deeds, and grace. In the Old Testament, circumcision was the mark of faith; in the New Testament, it is baptism. Faith and deeds must come from each one of us. Grace is evident in God's mercy and justice. St. Paul addressed the ignorance of the Athenians in a delicate but assertive manner in regards to their claim "To the Unknown God". "Therefore, since we are the offspring of God, we ought not to think that the Divine Nature is like gold or silver or stone, something shaped by art and man's devising. Truly these times of ignorance God overlooked, but now commands all men everywhere to repent, because He has appointed a day on which He will judge the world in righteousness by the Man whom He has ordained" (Acts 17:29-31).
Knowing how precious our faith is, and how undeserving we are of God's grace and mercy, we are inspired to preach Christianity to the world. Despite ridiculous arguments and ineffectual scrutiny of their time, a handful of fishermen did exactly that and as a result they changed the world over 2000 years ago. Our Lord Jesus Christ instructed His disciples and us, "Go into the entire world and preach the gospel to every creature. He who believes and is baptized will be saved; but he who does not believe will be condemned" (Mark 16:15,16).
God is compassionate beyond our ability to understand, and His many mercies are countless. Nonetheless, His expectations for eternal life with Him are clear. St. Paul expresses his gratitude to God for His mercy saying, "And I thank Christ Jesus our Lord who has enabled me, because He counted me faithful, putting me into the ministry, although I was formerly a blasphemer, a persecutor, and an insolent man; but I obtained mercy because I did it ignorantly in unbelief" (1 Timothy 1:12,13). Therefore, God's mercy will be extended to those who unknowingly and unwillingly lived in ignorance of Him throughout their lives; but their distance, barriers, denunciations, and convictions will remain.