We are far, far too nice and civilised for many atheists-with-attitude!
I advise taking a look at the comparitively well populated "The Thinking Atheist" forum. There verbal violence, swearing, personal insult between members etc is commonplace. That, added to a scoring scheme involving "likes" and "reps", seems to be successful in recruiting.
But, unless you have the right genes for that atmosphere it palls and, perhaps, apalls.
But, for many who enjoy, er, vigorous discussion it seems to work.