For example, a young man just starting college is murdered. He didn't get to live a long life, while someone else becomes a believer in their 40's.
The person in their 40's had more time to accept Jesus, yet the young man didn't. It seems unfair, but what does the Bible say?
Was the young man probably never would have been a believer anyway? Are we sometimes saved not only because we accepted Jesus, but by chance we survived long enough to accept Jesus as our God? Or does this not make any sense?
My position isn't popular, but when has that stopped me from trying to help?

I believe God has chosen, up front, who He wants in His kingdom. Those He has chosen will always choose for Him because it's in their nature to want Him.
It really doesn't matter if we die before we accept Christ. It is already established who would, if given the chance, accept the Lord. The advantage of living a full life is that it gives an opportunity for God to express the full range of redemptive activities in a person's life. If that life is cut short, God will not dock them for failing to express their full potential.
Those who aren't chosen are products of evil angels and evil men who make use of God's creation to produce human agents who are repelled by God. They naturally assume the nature of the ones who have influenced their coming into existence. According to Jesus, they are "planted by the enemy."
I do believe in free choice, but I also believe God has made His own choice, as well. And He never intended to produce rebels--just those He calls His children. Those He has chosen will be able to live with Him in paradise. Those who he has not chosen will be judged based on their deeds, some suffering many stripes and some suffering only few stripes.
The problem with not being chosen is that there is a natural propensity to reject Christ. And the result is Outer Darkness, which may be a more severe or a much milder punishment.
I know we have all heard that Hell is hideous and gruesome. But I believe we are told that the fire is simply to remove all sinners from God's paradise on earth--not to torture people. The suffering is simply the fact of being removed from Paradise conditions, along with the remorse of having done wrong.