Fair enough. My analogy to Islam is that I think there are circumstances in which members of a faith may certainly label others as not "authentically Muslim." I agree that in Catholicism, we should do so cautiously.  As a left-leaning Catholic I am all too familiar hearing that my vote for Obama meant that I was not a true Catholic, but I have no problem with the folks at Church Militant being labeled as not authentically Catholic. Maybe that makes me a hypocrite. Or maybe their views are so extreme that some separation from those extreme views is ok.