Some time ago I had a rather interesting discussion with a couple of friends as to what does it mean to be a member of a visible church and we decided to use, as a test case, the “highest” church possible there is to discuss the issue.
So the question is, what does it mean to be a member of the Roman Catholic Church? And I gave three possible solutions:
(1) Your name is on some parish registry or roll or you have some baptismal/confirmation certificate or something (the “administrative/bureaucratic” membership)
(2) Take communion at a parish on a weekly basis (the “living church” membership, because your membership is renewed “live” by literal communion with the Church)
(3) You believe everything or assent to a certain set of ecclesiastical documents (the “credal/confessional” membership)
Each definition is obviously problematic. One can simply go through the administrative bureaucracy of the Roman church and get one’s name “on the list” and then completely drop out of the parish after that. And given the way that the Roman Church rarely ever really publicly and administratively excommunicates anyone or strike anyone’s names off the parish rolls, then according to the “administrative” definition, One can be a practicising Protestant and be Roman Catholic on the list. (Dinesh D’Souza comes to mind here)
The “living church” membership is also problematic in that most priests do not know their members by name or face, and anyone can simply go up and take communion. And even in the case where the person takes communion is a well-known figure who is clearly not Roman Catholic or has been “publicly” denounced by some Cardinal or bishop, most priests will still not refuse them communion. In Europe, most priests won’t even refuse open Protestants from communion. (An interesting case in point was Stanley Hauerwas, American’s “Greatest Theologian” and a methodist back then, used to take communion from a Roman chapel in Notre Dame University and when one time a roman priest refused to give it to him, he simply joined another queue!)
Finally, the “confessional” approach would shrink the church to a very tiny “true believer” remnant who actually fervently believes and subscribes to the CCC while the vast majority of Romans hold beliefs and practices incompatible with the CCC, and some of them openly reject its teachings and remain both in both administrative and “living” communion with their church.
In short, the concept of being a member of a visible church actually makes very little sense without localised concrete empirical definitions and practices, and a sufficiently vast empirical bureaucracy or canonical polity becomes a mere unreal abstraction.
Of course, one can always say that one’s membership in the church cannot be captured by empirical definitions and is an essential mystery.
If you do, congratulations, you’re a Protestant and believe in an invisible/hidden Church.