1 Corinthians 10
16 The cup of blessing which we bless, is it not the communion of the blood of Christ? The bread which we break, is it not the communion of the body of Christ?
17 For we, though many, are one bread and one body; for we all partake of that one bread.

NKJV

We maintain that the bread and the wine in the Supper are the true body and blood of Christ and that they are not only offered to and received by upright Christians but also by evil ones. (Smalcald Articles III, 6:1)

In the Lord’s Supper the body and blood of Christ are truly and substantially present and are truly offered with those things that are seen, bread and wine. Moreover, we are talking about the presence of the living Christ, for we know that death no longer has dominion over him [Rom. 6:9]. (Apology of the Augsburg Confession X:4 [Philip Melanchthon], Kolb/Wengert p. 185)

No human words or works create the true presence of Christ’s body and blood in the Supper, whether it be the merit or the speaking of the minister or the eating and drinking or the faith of the communicants. Instead, all this should be ascribed solely to the almighty power of God and to the words, institution, and arrangement of our Lord Jesus Christ. ?For the true and almighty words of Jesus Christ, which he spoke in the first institution of the Supper, were not only effective in the first Supper; they remain so. They retain their validity and power and are still effective, so that in all places in which the Supper is observed according to Christ’s institution and his words are used, the body and blood of Christ are truly present, distributed and received on the basis of the power and might of the very same words that Christ spoke in the first Supper. For wherever what Christ instituted is observed and his words are spoken over the bread and cup and wherever the consecrated bread and cup are distributed, Christ himself exercises his power through the spoken words, which are still his Word, by virtue of the power of the first institution. He wills that his Word be repeated, as Chrysostom says in his Sermon on the Passion, “Christ prepares this table himself and blesses it; for no human being makes the bread and wine, which are set before us, the body and blood of Christ. Rather Christ himself, who was crucified for us, does that. The words are spoken by the mouth of the priest, but when he says, ‘This is my body,’ the elements that have been presented in the Supper are consecrated by God’s power and grace through the Word. Just as the saying ‘be fruitful and multiply, and fill the earth’ [Gen. 1:28] was said only once and yet is continually effective in nature, causing it to grow and multiply, so these words were said once. But they are powerful and do their work in our day and until his return, so that in the Supper as celebrated in the church his true body and blood are present.” (Formula of Concord SD VII:74-76, Kolb/Wengert p. 606)

The evangelists write that the Holy Spirit descended upon Christ in the form of a dove at the river Jordan. Again, he came upon the disciples on the day of Pentecost, in the form of wind and tongues of fire. Again, upon Mt. Tabor in the form of a cloud. Here [John] Wycliffe and the sophists may play wise men and say, “This dove is present without the Holy Spirit,” or, “The Holy Spirit is present without the dove.” We say, in opposition to both parties, that as one points to the dove, he rightly and properly says, “This is the Holy Spirit,” in virtue of the fact that here the two diverse beings, Spirit and dove, in some degree are also a single being, though not naturally or personally. Well, it may be called a “formal union,” because the Holy Spirit has deigned to manifest himself in such a form. Here the Scripture says precisely that he who sees this dove sees the Holy Spirit, e.g. John 1[:33], “He on whom you see the Spirit descend and remain,” etc. ?Why then should we not much more say in the Supper, “This is my body,” even though bread and body are two distinct substances, and the word “this” indicates the bread? Here, too, out of two kinds of objects a union has taken place, which I shall call a “sacramental union,” because Christ’s body and the bread are given to us as a sacrament. This is not a natural or personal union, as is the case with God and Christ. It is also perhaps a different union from that which the dove has with the Holy Spirit, and the flame with the angel, but it is also assuredly a sacramental union. ?Therefore, it is entirely correct to say, if one points to the bread, “This is Christ’s body,” and whoever sees the bread sees Christ’s body, as John says that he saw the Holy Spirit when he saw the dove, as we have heard. Thus also it is correct to say, “He who takes hold of this bread, takes hold of Christ’s body; and he who eats this bread, eats Christ’s body; he who crushes this bread with teeth or tongue, crushes with teeth or tongue the body of Christ.” And yet it remains absolutely true that no one sees or grasps or eats or chews Christ’s body in the way he visibly sees and chews any other flesh. What one does to the bread is rightly and properly attributed to the body of Christ by virtue of the sacramental union. (Martin Luther, [Great] Confession concerning Christ’s Supper, Luther’s Works 37 [Philadelphia: Fortress Press, 1961], pp. 299-300)

This, too, would be a fine interpretation, if the priest would with the elevation of the sacrament do nothing other than illustrate the words, “This is my body,” as if he wished to express by means of his action: Look, dear Christians, this is the body which is given for you. Thus the elevation would not be a symbol of the sacrifice to God (as the papists foolishly imagine) but an admonition directed toward men, to provoke them to faith, particularly since he immediately elevates the bread right after speaking the words: “This is my body which is given for you.” (Martin Luther, [Brief] Confession concerning Christ’s Supper, Luther’s Works 38 [Philadelphia: Fortress Press, 1971], p. 314)

Question: What do we do with the remaining consecrated bread and wine?

There is no doubt that it is not we who got it from you, but you who got it from us, that Sacraments are actions, and not persistent manufactures. But what is this peculiar rashness of yours that you would rather not abstain from this evil appearance which you know is a scandal, namely, that you mix the remains of [consecrated] wine and bread with [unconsecrated] bread and wine? By which example do you do that? Indeed, do you not see what dangerous questions you are raising, if you contend so much in this opinion of yours, that when the action ceases, the Sacrament [also] ceases? Perhaps you want to be considered a Zwinglian, and am I to believe that you are afflicted with the insanity of Zwingli, when you are so proudly and contemptuously irritating, with this peculiar and magnificent wisdom of yours? Was there no other way for you to avoid giving the suspicion to the weak and to the enemy that you are a despiser of the Sacrament, than to cause offense with this evil appearance that what is left of the Sacrament is to be mixed, poured in with [unconsecrated] wine? Why do you not imitate the other churches? ... For you can do what we do here [in Wittenberg], namely, to eat and drink the remains of the Sacrament with the communicants, so that it is not necessary to raise these scandalous and dangerous questions about when the action of the Sacrament ends, questions in which you will choke unless you come to your senses. (Martin Luther, [First] Letter to Simon Wolferinus [1543], in Edward Frederick Peters, The Origin and Meaning of the Axiom: “Nothing Has the Character of a Sacrament Outside of the Use,” pp. 207-08 [WA Br. X, 340-341])

Indeed Dr. Philip [Melanchthon] wrote rightly that there is no Sacrament outside of the sacramental action; but you are defining the sacramental action much too hastily and abruptly. If you do it in this way, you will appear to have absolutely no Sacrament. ...one must give this Sacrament a certain period of time, and a period of appropriate breadth of time, as they say, “in breadth.” Therefore, we shall define the time of the sacramental action in this way: that it starts with the beginning of the Our Father [orationis dominicae] and lasts until all have communicated, have emptied the chalice, have consumed the Hosts, until the people have been dismissed and [the priest] has left the altar. In this way we shall be safe and free from the scruples and scandals of such endless questions. Dr. Philip defines the sacramental action in relation to what is outside it, that is, against reservation of and processions with the Sacrament; he does not split it up within [the action] itself, nor does he define it in a way that it contradicts itself. Therefore see to it that if anything is left over of the Sacrament, either some communicants or the priest himself and his assistant receive it, so that it is not only a curate or someone else who drinks what is left over in the chalice, but that he gives it to the others who were also participants in the Body [of Christ], so that you do not appear to divide the Sacrament by a bad example or to treat the sacramental action irreverently. (Martin Luther, [Second] Letter to Simon Wolferinus [1543], in Edward Frederick Peters, The Origin and Meaning of the Axiom: “Nothing Has the Character of a Sacrament Outside of the Use,” pp. 210-11 [WA Br. X, 348-349])

The words of the Supper are known, plain, and clear in their natural and true sense. When I ask, “What is present in the Lord’s Supper and offered by the hand of the minister and received by the mouth of those who use it? Is it only bread and wine?” He, who is Truth itself, answers: “This is My body; this is My blood.” Thus Paul says, 1 Co 10:16, that a breaking and communion, that is, distribution and partaking or receiving takes place in the Lord’s Supper, and that it takes place by outward eating and drinking with the mouth, for he says, “Eat and drink.” Now, if I ask: “What is distributed and received when the bread is distributed and received in the Lord’s Supper?” Paul answers that it is koinonia, that is, distribution and reception of Christ’s body, etc. ... If, then, you want to know from Christ Himself, who instituted this Supper, who is Truth itself, and whom the Father commended to us from heaven to hear, what it is that is present in the Supper in, with, and under the bread and wine, and that is offered by the hand of the minister and received by the mouth of the body, He answers expressly, clearly, and plainly: This is My body, which is given for you; this is My blood, which is shed for you. (Martin Chemnitz, Ministry, Word, and Sacraments [Saint Louis: Concordia Publishing House, 1981], pp. 123-24)