"Billions of Muslims are not jihadists and anyway, I already said that Islam is exceptional when it comes to activity. Which is why many of its critics say it is not a religion, but a political movement."
You said the difference between religion and communism is that religions are "content with being windbags who do nothing but talk about their beliefs." Jihadists are unquestionably a religious group, even if they are a minority in Islam, so that's just plain wrong. Also, there are examples of in other religions who do more than just talk. You often ring the tocsin about the Religious Right here in America. Surely that's activism where the people involved do more than just talk about their beliefs. The settlers in the West Bank, especially those outside the main blocs, are largely there for religious reasons. Surely building villages on hilltops while fighting off Palestinian attacks is more than just being a windbag? And what about the Falun Gong? You're really just flat-out wrong here.
"As for the No True Scotsman issue, I don't accept that. Practice is fundamental to being a communist. Handing out pamphlets is at least political activity, it at least involves participating in a structured organization with a line, change of command, and discipline. If you're content with the current ruling class, and do nothing about trying to change it, then you can't call yourself a communist. And you can't point me to a single theoretical document anywhere by any leading light of the communist movement that says it's acceptable to do nothing."
Well, by the sound of that "activism" is so broad as to be meaningless. So the guy who votes CPUSA every election but keeps to himself isn't a communist, but the guy who hands out pamphlets on the corner for the irrelevant United Workers' Socialist Revolutionary Provisional Committee of North America (Marxist-Leninist) is?