That means that everybody I argue with--from torture defenders to pro-choice Catholics--is somebody I regard as a Catholic (assuming, of course, that they claim to be Catholic). They may be, as I think they sometimes are, Catholics in grave error. But they are Catholics nonetheless--sinners who are, like me the chief of sinners, stumbling along and seeking grace in our frequently stygian intellectual, spiritual, and moral darkness. If a bishop excommunicates somebody (that rare event) I will go with the mind of the Church. But I ain't excommunicating anybody. Still less am I inclined to regard anybody in the Church as my enemy (though I know there are numerous folk who regard me as theirs). I may tell somebody that they are Protestant *in their thinking*. But I will never tell somebody they ought to leave the Church for the same reason I won't tell a sick person to get out of the hospital. That's the bishop's job, not mine.
I don't think we are called by Christ to regard the members of the Church, including "the bishops" (that indiscriminate faceless mass) as "enemies". I think we are called to regard our brother and sister Catholics as brother and sister Catholics, even when they read the Reporter and despise us, and even when they hold much of the Church's teaching in contempt. You pick your friends. You are stuck with your family. Doesn't mean you have to agree with them. (Indeed, one of the things I love about the freedom of the Catholic intellectual tradition is that you really can disagree strongly with fellow Catholics about all sorts of stuff.) It just means you face the fact that if Christ calls them his brothers and sisters in baptism, then they are your brother and sister too.
So, unless a Catholic is a) excommunicated or b) specifically declares that he no longer wishes to be considered a Catholic, I will assume he is one. He may be a very bad Catholic either morally, intellectually, or spiritually. But then so am I, so it would hardly do for me to show him the door unless I want to show myself the door at the same time, which I don't since I need Jesus. So I will content me with arguing with ideas and not kicking anybody out (as if I have any power or right to do that).