As best that I can tell, the folks at Westboro follow the teachings of their pastor, "Whatshisname", not Jesus Christ. Therefore I do not regard them as Christian. Which means that your example has no relevance. As far as being Evangelical, they may be evangelizing something, but it isn't Christianity.
If you truly believe that there are Christian groups "that are extremely radical and capable of heinous acts" then you should try to back it up. So far, all you have done is make a false claim about Mr. Giles' column, and tried to use a non-Christian group's actions to try and paint other Christians as "radical" and "capable of heinous acts". This tells me more about you than it does about anyone else.