Yes, I think I use the term radical rather loosely, just for emphasis. If you describe yourself as atheist some people will say, Don't you mean agnostic? I have to reply that I really do mean atheist, I really do not believe that there is a god; in fact, I am convinced that there is not a god (a subtle difference). I see not a shred of evidence to suggest that there is one...etc., etc. It's easier to say that I am a radical atheist, just to signal that I really mean it, have thought about it a great deal and that it's an opinion I hold seriously.