You know people always come up with this question, I have a small comment, if you're really THAT concerned for these people why don't YOU go and make 100% sure that these people hear the gospel. Oh but a few disclosures and warnings first:
1. Make sure you're saved first so you wont be the hypocrite telling them they need to repent and trust in the Saviour Christ Jesus, when you yourself haven't done so.
2. Beware of the well expected hostility toward the gospel, if Jesus Christ was killed for offering Salvation to the lost world and claiming He is the Son of God and God himself, what can you expect will happen to you for preaching the Gospel?
3. Take heed, you may be imprisoned, beat to death, abducted, tortured, humiliated, insulted, spitted on, ridiculed, oh and yes be rejected. Christ was, why should you expect less?
But you know what, Christ came over 2000 thousand years ago knowing all of this would happen to Him and yet that didn't stop Him from calling all to repentance, teaching the Heavenly things His Father sent Him to teach, serving all those who were considered unrighteous, rebuking the Hypocrite Scribes and Pharisees, dining and fishing with sinners, and ultimately carrying a cross to calvary where He beared ALL of our Sins, where He took in the Father's wrath, died. And on the Third day resurrected beating death, Sin and Satan. So that one day, you my friend who don't believe in God or the Bible because, among other things, you think its unfair that people who haven't heard the Gospel are going to hell; could be saved.
You see, we have ALL sinned (broken God's law, The Ten Commandments: Thou Shalt Have No Other Gods before the Lord your God, Thou Shalt not make yourself a Graven Image, Thou Shalt Not Use the Name of the Lord your God in Vain, Thou shalt Thou Shalt keep the Sabbath Holy, Thou Shalt Honor Your Mother and Your Father, Thou Shalt not Kill, Thou Shalt not Commit Adultery, Thou Shalt Not Steal, Thou Shalt Not Bear False Witness [a.k.a. Don't Lie], Thou Shalt Not Covet your neighbor's anything. ) even the the indiginous people, those hidden tribes that are who knows where. ALL have sinned, and have fallen short of the Glory, or Standard, of God. The Bible says that the wages of Sin is death, and only a person who has NEVER sinned could pay that wage, this is why Jesus Christ had to die, He was the only one who could bear the sins of the world and who could take in the Father's wrath.
Isaiah tells us that He was pierced for our Iniquities (sins) so that by His blood shed on the cross we could be Saved from eternity in Hell, which where ALL sinners go.
You see when you realize that you are a Sinner, bound to go to Hell because of sin, the bible says if you repent of your sins and turn to the Only Saviour, Jesus Christ, He will save you. You will be Justified before God, because Christ has taken YOUR place on the Cross and has payed the price for YOUR Sin. God promises that all who repent and trust in Christ, will then receive the Holy Spirit who will change your heart of stone for a heart of flesh, and will give you a new nature (This is called regeneration) that will desire to do that which pleases God and will hate sin.
So what are you waiting for??