I actually said 'barely having' heard of Jesus.
Yes and i actually read what you said an answered your question from the description you gave me. If he is as you say a muslim teenager who dies in the mountain of afganistan then the only possible information he could receive about Jesus is from the quran and the qurans description of Jesus is a distortion. So the young guy would never have received the Gospel message.
And remember that Jesus is honored in Islam so every devout Muslim knows something of him.
What they know is a distortion of the truth and is therefore useless to them for their eternal salvation.
They must be told that:How much does one have to have heard of Jesus and his message?
God was manifested in the flesh through Jesus. Jesus was without sin He came into being by the power of God not via a human father, that His death atoned for the sins of those who would accept His death as atonement for their sins. That His teachings are the revealed will of God. That He was raised from the dead and ascended into heaven and that He will come again. That only through the atonement of Jesus can any man be saved from the Lake of Fire.
That’s the basics
As one grows in knowledge of Jesus they come to know more and more of His teachings as the teachings become known they must be accepted as the truth. Jesus must be believed if one can say they believe in Jesus.
All Praise The Ancient Of Days