“Where is their opportunity? Or did they not get to hear the Gospel for a reason?”
God is just. He reveals Himself to all to some degree, as Paul wrote. He reveals Himself more explicitly to some than to others, and doesn’t tell us why. But I suspect the parable of the talents may apply. The summary is: “For the man who has something will have more given to him and will have plenty. But as for the man who has nothing, even his ‘nothing’ will be taken away.”
http://www.biblegateway.com/passage/?search=Matt%2025&version=PHILLIPS
But no, I do not know everything and God hasn’t seen fit to give me any extra insight. I am content to know that God will be just. How that will play out? I’ll have to wait and see.
If you are suggesting that there will be salvation outside of Jesus Christ for those who have never heard the Gospel, you would be horribly wrong.
As the scripture says, all men are guilty before God, regardless of how much “light” they have received (Rom 3:19). As all men have received, to a certain extent, the law of God imprinted on their hearts, as well as the light of nature revealing the existence of God, therefore they are summarily rendered “without excuse,” (Rom 1:20, 2:14) and “as many as have sinned without law shall also perish without law” (Rom 2:12). And again, “for we have before proved both Jews and Gentiles, that they are all under sin; As it is written, There is none righteous, no, not one: There is none that understandeth, there is none that seeketh after God”(Rom 3:9-11). And again, all those who do not know God have no hope, and lack God in the world (Eph 2:12). This light, therefore, brings them condemnation, it is not a "degree of light" that could potentially save them.
And finally, “All that the Father giveth me shall come to me,” and, to “come” is to believe: “But there are some of you who do not believe... This is why I told you that no one can come to me unless it is granted him by the Father.” (Joh 6:37, 64-65), thus it cannot be claimed that there are those who are saved who exist amongst horrid cults or false religions who deny the Father and the Son, since all those whom the Father gives to the Son do not stand idle, but come rushing into the arms of the savior according to His plan and promise.
1Jn_4:3 And every spirit that confesseth not that Jesus Christ is come in the flesh is not of God: and this is that spirit of antichrist, whereof ye have heard that it should come; and even now already is it in the world.
If any man is in the world who never heard the Gospel, it was by the infallible power of God, and not by random chance, that he was left so abandoned. And, therefore, it was one of those whom God chose not to have mercy on, in accordance with His almighty sovereignty (Rom 9:18-21).
A denial of salvation in Christ alone is a horrid doctrine, and must be smashed by all the force of scripture.