My point is that Jesus himself foretold (several times) that not all who called on his name would really be his followers. He did not, however, lay out any detailed definition of how to tell one from the other. The parable mentioned implies very strongly that it would be very difficult to tell the wheat from the tares, and the similar parable of the sheep and goats had essentially the same meaning.
I have my own criteria for those I consider fellow-believers, but I don't feel that I have the right therefore to publicly attempt to deny others the right to call themselves by the name "Christian."
I have no objection if you want to give your own opinion and say, "I don't consider a particular denomination to be Christians." I don't think any human has the right to speak with authority about exactly who Christ considers to be his followers. We're just all too fallible to make such ultimate judgments.
IMHO