I’m not sure it will clarify or not, but for what it’s worth. We in the LCMS do not accept denominationalism. We do not believe in the branch theory of the Church. We recognize that our practice of closed communion is exactly what would be appropriate for the entire visible Church on earth. We believe that what we believe is precisely what every jurisdiction/communion SHOULD believe, because it is – we hold – nothing other than what the Scriptures teach.
In other words, we don’t regard those who hold to a different Confession as just “another denomination.” We regard the other confessions to the extent they differ from ours to be falsifications of the truth. As offensive and prideful as they may sound, it’s not intended to be anything less than what (until very recent times) EVERYONE believed about their own confession.
So we act in our communion discipline *as if* we were the legitimate heir and successor to the Catholic Church of the West. That’s a self-understanding derived from our Lutheran Symbols. We do not claim to be the only jurisdiction in this Catholic Church of the West, purified by the Gospel. We recognize other particular churches around the globe in whom the same faith resides – from the churches of the Archbishop of Latvia, to the churches of the Archbishop of Kenya and the Bishop of Southern Africa and the President of the LCC, and a bunch of others. Consequently the notion that our altars are closed to non Missourians is actually not at all accurate.
In the corrupted state of the Church in which doctrine that we cannot but regard as false and dangerous is enshrined in the confessions of other jurisdictions, this leads invariably to acknowledging in them that while members of the Church Catholic may well reside in their midst (in fact, most certainly DO), nonetheless those Churches by the acceptance of various falsehoods alongside the truth of God, cannot be acknowledged as true sister churches on a par with our Synod. Again, I know it sounds horrific to the ears of those who think denominationally, but if you think confessionally it makes perfect sense: confessions can be entirely pure, somewhat corrupted, or totally destructive of the Christian faith. We tend to put almost all the other confessions (Anglican, Reformed, Roman, Orthodox) as “somewhat corrupted.” Totally destructive would be something like a Mormon or JW confession.
So back to the assumption that an LCMS person holds the pure confession – that IS the assumption we would make, unless the person in question gives evidence that his participation at our altars is in fact a lie – that he disagrees with our Lutheran confession of the Christian faith as expressed in our Lutheran Symbols.
I’ve probably offended all my ELCA friends and many of my Missouri ones by the above, but I think it’s clear that until we can get the differing ecclesiologies understood, there’s no hope of anyone understanding our practice of responsible communion (my preferred term), which takes seriously into account the nature of one’s public profession at a given altar (where, as Pr. Speckhard says, he or she is willing to accept correction).