A student asked me yesterday, "What can I do to not be depressed if a friend dies, and I don't know if they knew Christ? How can I not be really sad about that?"
The question took me aback somewhat, since I had never been asked that before. What a hard thing to deal with!
My response, after some thought was, "I think we should be sad. However, we shouldn't focus so much on thinking 'I wish I had done this, or gone here.' Instead we should let it motivate us to reach others, so no one else has to experience this."
It wasn't the happiest response, but I think it was necessary, and, appropriately, it was met with tears.
Nothing should be more saddening than when someone leaves this life without knowing Christ. Likewise, nothing should be more motivating. However, like all difficult situations, we have to accept God's control of the circumstance and allow it to motivate us to further action. We should be so motivated by this experience that we dedicate our whole lives to never let it happen again.