PZ Myers’ teenage daughter explains two methods of successfully discussing atheism:
It’s moderate atheists’ job to speak nicely to theists and get them to hear the message, but it’s the militant atheists’ job to get the moderates out of the closet and active. Do they scare away some theists entirely? Probably, but those are most likely the most unchangeable anyway. And it still doesn’t outweigh the need for angry atheists and their “rudeness”.
Edit: Updated to include a link to the original post in the first sentence.