However, the "communism" I was discussing was not the kind found in small, rural communal colonies. The Amish, Hutterites and the like, keep to themselves and do not attempt to force their ideology on others. The same cannot be said for communism.
Revolutionary Marxian socialism or Marxist-Leninist communism is a very different beast from the examples you have given.
I assumed that would be clear in my post. Apparently it wasn't.
Yes, that is one big difference. Coercion is the problem, not that Christian churches have not engaged in the practice (the Inquisition).
But even when it is voluntary such as the kibbutz movement in Israel or the Jamestown colony, it is hard to get it right.
I think it is very important to study communal societies because under some circumstances such as new colonies with minimal populations in remote places (like Mars perhaps), it may be what needs to be done.
Notice that you very seldom see leftists pointing to Hutterites as an example of successful communism. They just can't bring themselves to admit that dedicated Christians can succeed where atheists fail.