If a man does not know Christ at all, how can he possibly be sent to Hell for that? He will be sent to Hell for other sins. Imagine a culture that has not even encountered Judaism, let alone Christianity. The Church teaches that even this isolated culture has the basic ideas of virtue inherent in all human beings, implanted by God: prudence, fortitude, temperance, and justice. Were a tribesman totally ignorant of Christ to be prudent, courageous, moderate, and just according to the ways of the conscience, there is no doubt that God would save that person in His mercy.
Ignorance really does count for a lot, since Christ said that only those who know the Father through the Son of God may enter Heaven - but we must know the Father with trust and childlike love of truth. This describes many cultures that were or are ignorant of Christ. The Gospel for today (the Sacred Heart) records our Lord saying that He makes the Father known “as it pleases Him”. If it pleased our Lord to allow millions to go without the Gospel until we had brought it by our lips and our deeds, then it was Providence. All things work toward the last End, the final Day.
Now, Moslems in this modern world can see and know about Christ with the click of a mouse button. There’s no excuse for not knowing about Him… but if you don’t truly Know Him, there’s a possible aside. We can have just Moslems, living in faith, hope, and charity without even knowing it. Some are indeed innocent of guile, but we really can’t say there’s any excuse for rejecting Christ if He is known.
Don’t worry! Don’t freak out! Calm down! The love of God is beyond the stars.