I have many non Christian friends, and as people they don't bother me. I don't feel like I have to lecture them on Christianity all the time, but it bothers me when sometimes people talk hatefully of the religion but haven't researched it. Then, I try to tell them about the ideas just so they at least can make an informed decision. I try to be a Christian in my actions (doesn't always work, alas) and lead by example; but that still needs work.
I hope this won't be taken as something offensive about non Christians, I just know a few people like that: sometimes it bothers me if people make fun of the faith; because I wish that they saw what I see in it.
I think it's God's job to assign people to heaven and hell, and I believe that not all Christians are guarranteed heaven and not all non Christians are guarranteed hell. Since we know next to nothing about it, it's not our job to judge people like that. So while I don't picture non believers in hell, I discuss religion with many of my friends; and it's an interesting discussion because everyone gets to share their views. They tell me what they believe, and I tell them about Christianity. I used to be an atheist, and I thought that Christianity was really shallow. But when I learned more about it, I really liked it. So maybe some people just don't have the information, and that's when discussions are useful.
But it's not like I make friends with non believers just to tell them about my faith
we talk about many things and they also make great friends. I guess I just like discussions 
and I'm always interested in their views also whatever they are.
CS Lewis once said that we all have a responsibility in how we affect other people; because we have a part in them going to heaven or hell. So I guess I good rule is to just treat everyone in the right way, whatever their faith.
