How about those who born in other religions who have already a deep conviction. It is definitely harder for them to accept the Bible. If they cannot be saved, is it unfair for them if compared with those who were luckily born into a christian family for they have a bigger chance to trust in God?
It is tempting to be sentimental about sincere people who believe in religions which do not teach the truth. We should remember that, biblically, one is not saved by being a good person or by being sincere. We are saved by the blood of Jesus and through faith in the blood of Jesus. Like Paul said to Timothy: "Watch your life and your doctrine." Jesus said that the true worshippers of God must worsip in spirit and in truth. Jesus said "I am the way, the truth and the life; no one comes to the Father except through me." Peter said concerning Jesus "there is no other name under heaven given to men by which we must be saved." I believe that as followers of Jesus we will be better off accepting what Jesus and the inspired scripture says rather than be caught up in sentimentality. People are not saved by following Mohammed or Confucius.
You wonder if it is fair for God to judge such people. I say that I trust God’s justice. I am prepared to admit that a person born in a "Christian" country or family may have more opportunity to respond to Jesus, but neither is being born into a Christian family a guarantee of acquiring saving faith, nor is being born into an atheist or Buddhist family a guarantee of not hearing about and responding to Jesus. God is perfectly just. He is able to judge our hearts. Fortunately, God is the judge of all men and I am happy to leave judgment with him. If, at the last day, God chooses to accept into heaven some of those who did the best they knew how with what they were given, but never came to believe in Jesus, I will be content with that. The more who make it to heaven the better as far as I am concerned. However, I believe we will do well to hold out the word of truth–to call people to follow Jesus, and to not let sentimentality cause us to be complacent. I am not confident at all in the salvation of anyone who does not repent of their sins and put their faith in the saving blood of Jesus.