If someone never got the chance to hear about God, will they still go to heaven?
This question encompasses many things, so I'll try to be as complete as I can.
First, the Bible is clear that mankind inherits a basic sin nature due to Adam and Eve's fall from grace after eating from the tree of the knowledge of good and evil. They didn't have the responsibility of avoiding evil before then as they didn't understand it. After they knew good and the absence of good it became requisite for them to always choose good in order to interact with a Holy God.
This is impossible for anyone to achieve. It is clear that all have sinned and come short of the glory of God. Jesus avoided this due to having God as His Father. Jesus Christ came into the world to be a perfect sacrifice for mankind's sin and to reconcile those who accept His sacrifice on the cross to a Holy God (Rom. 3:23, 5:8-21).
Adam and Eve were responsible for training up their children in the fear and admonition of God (Eph. 6:4). Abel would say they had mixed success. So even from the first generation, there was a failure to properly communicate this to the next generation. Clearly, early on they weren't teaching about Christ, although they could have been teaching about the sacrifice to come that would reconcile themselves to God (Gen. 3:15). This blood sacrifice system became more formalized in early Judaism as the sacrificial system pointed toward Christ (though when He came they didn't believe He was the one).
Parents today must do all they can to instill the Christian ethic into the next generation and cause them to want to accept Christ as Savior and to live for Him. But all generations have had problems with this and have varying degrees of success. Where Satan gets hold of a body of people, sometimes complete groups of people can stop hearing of Christ and the road to salvation. The world is enticing and it is easy to get people to go after their own lusts rather than live a life of holiness. Satan works very hard creating false religions and doctrines to lead people astray.
So what about those groups where generations of people drifted off without anyone in the current generation knowing about Christ? Are they simply lost? The Bible is not 100% clear on that subject. It is clear that part of the work of the Holy Spirit is to convict mankind of sin. The "conscience" of popular literature is actually the Holy Spirit telling you what is right and wrong for you to do. I believe He has worked in every heart of every age trying to draw people to God and away from Satan and self. We are warned that even as Christians, if we turn away from Christ and ignore this voice for a long enough period of time that He will eventually give up on us, but from the start He is always there.
So every person has heard God's correction as they have carried out their improper or downright evil actions and nobody can stand at the great white throne judgment without knowing why they are there. Yet Rom. 2:11-21 would appear to give some ambiguity in that regard. I had always wondered about that passage till I heard a missionary speak about a missionary going to a Pacific island where nobody from the outside world had ever visited. When he got there, the natives said that a spiritual leader in the past had had a vision about a man dying on a tree and they worshiped that God. He explained Jesus to them and they all agreed that they were talking about the same event.
So I am unwilling to say with certainty that there is no way that God could reach someone or some people unless a missionary or evangelist does the work and tells them. I think that God is doing a lot of work that we never see. He doesn't want anyone to perish. He wants everyone to have everlasting life.
Of course, it was up to that spiritual leader to choose to lead his people down the new path he had just seen, just as it is the duty of every individual who hears about Christ, and now you too, to decide what they are going to do about the Gospel Message.
For the Bible is clear on one more thing. If you hear, as you now have, about Christ and then reject Him, there is no other covering for your sin. If there is any grey area, and as I said, I'm not 100% willing to count God out in reaching people that we don't think have ever been reached, then you are no longer in that grey area once you reject Christ. If you reject the one way for you to be reconciled to God, then you can have no part in Him. That is clear.
I don't know how often God intervenes like He did with the inhabitants on the Pacific island. Maybe He just does that every few generations and then leaves it up to the person He gave the vision to or the dream to to communicate it to the people. Maybe if that person fails, then the people are just out of luck for a long while to come. Maybe He gives several chances.
Maybe, if you truly have never heard of the gospel, He judges you based on how well you obeyed the Holy Spirit and whether you were repentant when He talked with you about your sin. In other words, maybe He judges your heart and whether you acted like a Christian should act rather than the religion you label yourself with - as long as you haven't heard about and rejected Christ as Rom. 2 might imply.
But don't count on that and don't put off the decision to the last minute. Don't have as much fun in the world as you can hoping that at the last minute you can accept Christ and be saved. You never know when you are going to die and it may happen so suddenly in a car accident or by stroke or by heart attack that you have no time to accept Christ.
I do know this. In this day and age, with the internet prevalent in most parts of the world, there are few who have not heard at least something about Christ. They may not have been effectively witnessed to, but they have heard about God and probably heard about Christ. Many, many, many people have laughed God off and called him a fairy tale or worse. I would have to say they were out of the grey area as well.
Always remember Christ's warning about the way to eternal life in Mt. 7:13-14. Wide is the gate and broad is the way that leads to destruction and strait is the gate and narrow is the way that leads to eternal life. So even though there might be some remote chance for those in a truly grey area, the reality that Christ talks about is that it is difficult to make it into heaven and not many are going to make it.
Even in His day, when He related the story of the rich man and the beggar Lazarus, the rich man had company in the torment compartment of sheol. The grey area wasn't very big, if it existed at all because the rich man wanted his living relatives warned about what awaited them if they didn't straighten up and accept Christ. He knew they were out of any grey area already and were destined to join him (Lk. 16).
Make the choice for Christ today - don't put it off.