Time magazine author Andrew Sullivan recently outlines the distinction between Christians and 'Christianists' in his article, "My Problem with Christianism". The distinction is similar to the difference between Muslims and Islamic fundamentalists, or 'Islamists' as some call them.
LINK HERE (note: this article has since been changed to require subscription to the site, which it didn't at the time of posting. Sorry!)
Along a similar theme, Michelle Goldberg is interviewed on her new book Kingdom Coming: The Rise of Christian Nationalism by the NPR. In this 40 minute audio program, she goes into detail about the political objectives of the Christianists.
I think it would be helpful to start distinguishing between radical Christianists and Christians, if for no other reason than the fact that more reasonable moderate Christian voices are being lost in the mix.