Radical or Extreme?

We have a pretty good idea of what radical Muslims look like. Or at least what radical extremist Muslims look like. Or at least what "they" say they look like. Supposedly they are following the teachings of the Koran as completely as they can. Supposedly they look to Mohammad and imitate him as closely as they can. Was Mohammad a radical? Was he extreme?

What does a radical Christian look like? Or maybe we should ask what a radical extremist Christian looks like. Do we know how to be one? Would we be able to tell if we saw one? Some people think radical Christians aren't any different than radical Muslims. Is this true?

Would it be safe to say that radical Muslims and radical Christians are people who live their lives based on what their respective holy books teach then and who attempt to imitate (follow) the person who founded their respective movements? If so, then we should be able to determine the value of the movement according to the founder and according to the kind of behavior "radical followers" demonstrate.

Or is that simply extreme?