“Take and eat, this is my body.” This word is the whole gospel. You will observe and understand that it says nothing about a sacrifice or a good work but about a present and a gift, which Christ offers and gives to us, and which we should receive and with faith appropriate and hold fast. He tells you to take and keep, and would you make an offering of it and give it away? How can you say to God: “I give you your Word”? Neither can you say to another person: “I am offering God his Word on your behalf.” On the contrary, you should say: “Dear Lord, since you say that you freely give it to me, I receive it with gratitude and joy.” Just as you cannot make out of the gospel a sacrifice or a work, so you cannot make a sacrifice or a work out of this sacrament; for this sacrament is the gospel.
Therefore, in this matter no one can achieve anything for another person. Each one must believe for himself, just as I must believe all the Gospels for myself. I cannot hear or believe or keep for any one else so much as a single letter of the gospel, even as I cannot be baptized for any one else. But a good work I can always do to another person and for another person. Indeed, I have to do them for somebody else or they are not good works. For example, I can pray for you, serve you, work for you, suffer for you, and so forth. There is a great difference between faith and good works, just as vast as the difference in value between the tree and the fruit. Fruits disappear and return each year, but the tree remains always. Faith also remains always, but works disappear. In such a shameful way have they misled and deceived us that we go looking for good works and fruits when we should be looking for faith and the tree.
Be careful, therefore, to stay on the track. Don’t let anyone pull you away from the Word through any statement of man, be it Augustine, Jerome, Bernard, or even an angel [Gal. 1:8]. “The elect will be led astray,” says Christ [Matt. 24:24]. Therefore we cannot build on the mere word of one of the elect saints, without Scripture. Christ has warned us faithfully enough, and our own experience has probably taught us, that saintly men can make mistakes and have made mistakes. If our opponents complain that we have degraded and dishonored the sacrament because we have not let it become a sacrifice, then answer that we have not let the sacrament become a sacrifice for the very reason that we do not want to degrade and dishonor it as they do. It is a great degradation of the sacrament when a person ascribes nothing more to it than he ascribes to a good work. No good work can free us of our sins or give us grace or life or salvation. But this sacrament does give life, grace, and blessedness, for it is a fountain of life and of blessedness.
“The Adoration of the Sacrament”, Luther’s Works, Volume 38, pages 288-289