Hmmm...I always kind fell into the thinking that God is more than adequate to read the hearts of all men. And while I believe that it's unlikely that many, if any are saved without hearing the specific Gospel of Jesus Christ, I do think that there is merit in the possibility of a proper response to "Christ revealed in/through creation" leading to accountability one way or the other.
Scriptures;
John 1 1-5 - Isn't this a clear declaration that Christ is imprinted in some identifiable way in all of creation. I am by no stretch advocating any form of pantheism here, just Christ revealed throughout all that's been created.
Which leads to Romans 1 and more specifically, Romans 1:20 "For since the creation of the world His invisible attributes, His eternal power and divine nature, have been clearly seen, being understood through what has been made, so that they are without excuse."
It pretty clearly states that the probable eternal destiny of man dying without hearing of the Gospel of Jesus Christ is hell. But, it also implies that God in his infinite wisdom and grace, is able to judge a man's heart, once again, based on his response to the revealed Creation of and through Christ.
This is more or less thinking and wrestling through scriptures aloud. I've no desire to argue about it or get into a tussle over Cal's five.