Honestly, I think that most Christians believe that atheists are just people who haven't heard the 'good news' about Jesus. Not only is it ridiculous for them to think they could convert anybody, but it's delusional to believe that we'd even give them a second of thought. It's very hard for them to understand that anybody who isn't religious could have actually given Christianity some thought and then rejected it. When telling one of the latest proselytizers recently that I rejected Christianity for what it truly is, he responded with the comment that I just must not have understood it. I think this is the motivating factor for many of them. We non-theists just haven't had the bible explained to us correctly, and we're only a few quotes from turning our lives over to Jesus.
Even if the open windows of science at first make us shiver after the cozy indoor warmth of traditional humanizing myths, in the end the fresh air brings vigor, and the great spaces have a splendor of their own - Bertrand Russell