During the N.T. era many lived their lives and died without ever hearing the Word of God. And since salvation comes only through the hearing of the Word of God, failing to hear it could only mean that they were never saved.
Think about the 1st century, or 2nd century, or 3rd century, AD. Were there people living in South and North America during those times? Yes, of course. The Mayans had a calendar system that had a starting point many thousands of years before the birth of Christ. Obviously then, the Mayan civilization existed. Real people. Men and women. Lived their lives on a continent that was not reached by the gospel until many centuries later.
What of those Mayan people? Or what of the American Indians that lived in North America? Or the Aborigines that lived in Australia? Or the people that populated numerous islands in the South Pacific region? Many generations of them lived and died without ever hearing a single word from the Bible.
Was God unrighteous towards them? Was God not fair with those people?
The fact of the matter is, that we can know absolutely that if a tribe, or whole nation of people, lived their lives without ever hearing the gospel – it meant that none of them were God's elect people. And since none of them were God's elect people, the Lord was under NO obligation to send forth the gospel to them.
Matthew 15:24 But he answered and said, I am not sent but unto the lost sheep of the house of Israel.
The Bible teaches that the gospel was sent forth to seek and find in order to save only those people chosen by God to receive it before the foundation of the world. God obligated Himself to save the elect. That's it. Therefore God was under obligation to send forth the gospel in an evangelistic way unto salvation only for the sole purpose of saving those few elect people.
This is why, once God finished saving all that were elected to salvation, on the day of May 21, 2011, He could then end His salvation program and cease the sending forth of the gospel in an evangelistic way. God is under no obligation to send forth the gospel to people that are not chosen to obtain salvation. And since God is under no obligation to send forth the gospel to the non-elect, there is no injustice done. There is no unfairness or unrighteousness at all.
Some say God would never allow people to be born and live in the world for, perhaps, 22 years (23 inclusive) without there being the possibility of salvation for them. All that can be said is that this position is not well thought out. It has not taken into consideration the fact that God has already allowed, during the New Testament era, and that when the Day of Salvation was in effect, for many nations and many generations of people to live out their lives in various places without any hope of salvation for them because the Word of God never reached them.
Again, the Lord is under no obligation to send the gospel to the non-elect. No matter what point in time it is. Old Testament. New Testament. He does no wrong by not choosing them to become saved and by not sending them a Word to save.