I have one professor at college who believes that Christians should have as little contact with unbelievers as possible. Which makes this notion further right field is that he is the religion department. Sad, especially since he is a pastor as well.
Recently I picked up The Radical Reformission by Mark Driscoll, in which he critiques the evangelical church's method of sharing the gospel. One criticism he made is that door to door evangelism is more like, "Duck, Duck, Damned." In a rather literal sense, because one expects a person to come to a saving faith because of the information that you present before them. Instead, what we see Christ doing is preaching truth and grace wherever he goes, but he focuses on those who he has a relationship with.
How should we share the gospel then?
1.) Love Christ with our whole being
2.) Show Christ's love by being faithful to Him in all things: including relationships and truth
--This implies that we should make friends with believers and unbelievers alike, as we do so we need to guard our hearts to keep our hearts from sinning.
3.) demonstrate authentic faith in Christ through all of your life, we need to lean on him as we struggle.
4.) the gospel is instead presented naturally in the context of friendship (through word and deed). Live a Christ centered life, lean on Him through all failings, look to Him through all things, with this lifestyle you will naturally share His love with others.
5.) trust in God to do the work as He pleases (After all He called all who believe in Him, to Him.)