Sometimes the suggestion is made that we practice a closed table in order not to bring judgment on a person who might be communing unworthily. We admit that such a person is a believer, and we stress that we're not actually judging him or her. The Formula has always seemed to slam the door shut on that. It states without hesitation that no genuine believer, so long as he or she retains a living faith, CAN receive the Supper to their judgment.
So if that is ruled out as a reason not to commune someone who might want to receive at the altar in a Church of the Augsburg Confession while holding to a different confession any other week, what's left but to open the table?
What if, though, the reason you decline to commune such a person isn't because it would spiritually damage them, but because it would spiritually damage others? What others? All those who would then conclude that the error of the confession of that person's home church wasn't so big or important; and by implication that confession of the truth itself simply isn't a big deal.
Can one seriously read the pages of the NT and not realize the concern that rings through them to avoid error, to beware of it, to mark it and steer clear of it? No, I wouldn't commune someone who attends a church that teaches that Baptism is a human work, that a human decision saves, that what is received in the Supper is a remembrance of Christ's body and blood, or that the body and blood of Christ are sacrifice that can be applied by the priest to ease the sufferings of those in Purgatory! Yes, the person may say: "But I don't believe that; what I believe is that it really IS His body and blood!" That doesn't alter the damage done to the Body of Christ when I treat the individual as the be all and end all, and ignore the wider implications of where they regularly gather to be fed, taught, and corrected. Here's the shocker: IT JUST MAY NOT BE ALL ABOUT YOU.
Hard to fathom in this day and age, I know, but I have come to believe that people hate closed communion chiefly for this reason: it is a crystal clear confession that the faith simply isn't now and has never been an individual matter, you aren't the center of everything, and whether or not you will get your feathers ruffled and leave in a huff won't alter the facts one little bit. Is the Body and Blood that redeemed your sorry hide as well as mine upon the altar? Indeed it is. Was it given for you and for the forgiveness of sins? Indeed it was. Does the person receive it worthily who comes believing our Lord's words and promises? Indubitably. Does that mean we are free to treat a person of another confession as free floating agent, an individual? Absolutely not. We have to love them enough to break the news: none of us stands apart from his public confession; all of us are part of a confession by virtue of where we gather to be fed, taught, and corrected. Koinonia. Christians never stand apart from, but within, the Church and so within the confession of a specific congregation.