When talking to unbelievers about salvation, it is not uncommon to hear the question, "what about those who never had a chance to hear the gospel; is God going to punish them?" This question can be asked in one of two attitudes.
The first view is that God is either going to save everyone or else he is a cruel God. Usually this is the attitude of someone who wants to justify doing things their own way, regardless of what the Bible says. It really doesn't matter how you answer them, they are not going to change anyway. The best answer I can give to that sort of person is to turn the question back on them. I won't speak where God has not spoken, as to someone else's situation, but since you aren't in that condition what are you going to do about your own salvation? If you can no longer plead ignorance before the judgement bar, what will your plea be? Don't worry about others you don't know until you worry about yourself. "And the times of this ignorance God winked at; but now commandeth all men every where to repent." (Ac 17:30)
The second attitude is one of true concern for the lost. The speaker is already a believer, and is concerned about those who may not be. But they may also be concerned that God will condemn a person arbitrarily, and they aren't sure they believe in that kind of God. Perhaps such a person can be comforted by reading Acts 8 and 10. In the former chapter a servant of the Kandake (a title not a personal name) of Ethiopia, a Jewish convert, is earnestly studying the scriptures to know the will of God. A preacher is miraculously sent to him and he hears the gospel of the Christ. In the latter chapter Cornelius the Centurion, a Gentile, is told in a vision where he can learn about the will of God for him. He sends for Peter and becomes the first Gentile convert to Christianity. While today it probably isn't done through miracles, we see that God ensures those who want the truth will get it. Does this apply to the lost but seeking soul in "darkest Africa?" I think it does. God will see that he learns the truth (and if he doesn't, who am I to judge God?).
The real question then, is not what about those souls who never heard the gospel. The real question is: If I am the one God calls to tell a lost soul about the gospel, am I listening to Him, like Philip and Peter?
How then shall they call on him in whom they have not believed? and how shall they believe in him of whom they have not heard? and how shall they hear without a preacher? And how shall they preach, except they be sent? as it is written, How beautiful are the feet of them that preach the gospel of peace, and bring glad tidings of good things!" (Ro 10:14-15)
Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you alway, even unto the end of the world. (Mt 28:20)