Tell him that "line" as his pastor calls it, is called death, so as long as there is life in him there is hope.
He probably feels like that because,as any human would, when there is lack of God there is a desire, an emptiness, a void.
If he is longing to know God more you should help him. Teach him more about the Bible and get closer to God together.
It is actually a good thing that he recognizes that there is something missing. That closeness to God, the fact that we need to have a personal relationship with God, not just a heaven/hell concept.
So I would see that desire as an opening to preach to him the word of God put his focus more in God's goodness, mercy, compassion, and forgiveness.
When you focus more on God's goodness, you fall more in love with him and the least you will want to be away from him.
If you only focus in not trying to sin just because you don't want to go to hell then you'd probably end up failing.
Like that, whenever he feels the urge to sin again, he'll remember how much God loves him and how much he will be hurting him. Right there and then he can ask God for strength to overcome sin.
A question; has he already taken the steps in the plan of salvation?
If not, I'd say that's a good place to start.
He will see a complete 360 degree change when he starts having a true relationship with God.
Pray for him and pray to God to help you be a good spiritual friend as well. ^_~