Hijacking some words from David Schütz (and frequently bandied about by RC or Orthodox apologists as the argument that the corpus mysticum must then correspond to the visible corpus verum). And it is perfectly true: our Lord HAS a visible body. Do you see the body of the incarnate Lord now? No, you don't. What do the Apostles say?
"Though you have not seen Him, you love Him. Though you do not now see Him, you believe in Him and rejoice with a joy that is inexpressible and full of glory." 1 Peter 1
"Beloved, we are God's children now, and what we will be has not yet appeared; but we know that *when He appears* we shall be like Him, because we shall see Him as He is." 1 John 3
Our Lord's very real body, born of the Most Blessed Virgin, is to us at the moment invisible, an object of faith. And this is so even in the Holy Eucharist. That will, of course, cease to be the case at the Parousia. Then we shall indeed "see Him as He is" and such seeing shall utterly transform us so that we shall be like Him. And, as St. Paul said in Colossians, "THEN we shall appear with Him in glory." (Col 3)
The Church, as an eschatological reality, remains in this age - the age that is coming to an end - essentially something UNSEEN. Hence, "I BELIEVE in one, holy, catholic and apostolic Church." You can't see it. No Roman Catholic or Eastern Orthodox can see it. The Church isn't fractions; she's never less than the whole. And that's the vision of Church that we WILL see on the Last Day - the one assembly of all the saints, the people of God, gathered before the throne of God and of the Lamb. Think Revelation. Even for a Roman Catholic or an Orthodox Christian, the overwhelming majority of the Church remains NOT SEEN - for so many have died and been gathered to God's nearer presence awaiting the day of resurrection - and they, whom we do not see, are no less Church than we who continue to journey here below.
So don't give in to the apologists' argument on this one, dear Lutherans. The Church, as something eternal, is by very definition NOT SEEN (see 2 Cor. 4:18). The Church, as an object of faith, is by very definition NOT SEEN (Hebrews 11:1). And what saves this from falling into Platonism and the realm of mere ideas is the simple fact that to both of the above, the NT teaches us to add: YET. NOT SEEN YET, NOT SEEN FULLY IN THIS AGE. But she will appear - and it will correspond exactly to the appearing again of our Lord Jesus in the body He received from the Blessed Virgin - and what a glorious and joyous Day that will be!