People talk about this like it’s wrong without (usually) coming out and saying so. “Well, it’s not like she was proselytizing; she just answered a question about her beliefs,” or “They’re just running a clinic; it’s not as if they are actively proselytizing,” as if proselytizing were illegal, or disreputable. Maybe they want it regulated along with Alcohol, Tobacco, and Firearms. But it’s not yet illegal, at least not in the U.S. It is pretty clearly frowned on by the government. People are keen to stop proselytizing because it annoys Muslims and atheists. Of course we’re talking about Christian proselytizing here. All other kinds are fine, and some are almost obligatory today.
It’s important Christians resist this view of proselytism, even when it’s merely implied, because it has the effect of justifying restrictions on freedom of religion. The people who want to replace freedom of religion with freedom to worship would be most happy to make it illegal for Christians to seek converts, and they’ll find plenty of allies. We don’t need to help them ourselves. Proselytism is simply free exercise of religion. Denigrating it, or silently endorsing its negative connotation, does not advance the Gospel.
I can’t find the anecdote right now, so this is from memory. A well known preacher had stood on the street corner for an hour, urging people to repent and follow Jesus. During a pause while the band played, he fell into conversation with a Christian passer-by who objected to his preaching. “That stuff about Hell and repentance and Jesus being the only way, that turns people off; that’s not the best way to share the Gospel.” The preacher thought, then said, “You know, I don’t much like it either. How are you doing it?”
UPDATE 11 October 2013: I think proselytism is what other people do. So no True Christian proselytizes; he evangelizes, doing charity work and letting the Gospel speak for itself. Evangelism as contrasted with proselytism is like “more Jesus, less religion” – religion is what he and they do – those people over there. We are just following Jesus; though sometimes you might stray a bit from the path, brother.