As soon as…
The Formula of Concord famously says in regards to the Holy Supper: Therefore, the proper meaning and sense of the oft-mentioned Augsburg Confession can and should be derived from no other source more properly and correctly than from the doctrinal and polemical writings of Dr. Luther FC SD VII.41 Concordia, and this immediately before treating of the consecration of the Supper. The Augsburg Confession, of course, asserts “Our churches teach that the body and blood of Christ are truly present and distributed to those who eat the Lord’s Supper. [2] They reject those who teach otherwise.” AC X Concordia
Certainly to be held quite highly among Luther’s polemics on the Supper is his famous 1526 The Sacrament of the Body and Blood of Christ—Against the Fanatics (AE 36:329ff.) In this work, Dr. Luther makes a most interesting statement:
For as soon as Christ says: “This is my body,” his body is present through the Word and the power of the Holy Spirit. If the Word is not there, it is mere bread; but as soon as the words are added they bring with them that of which they speak. (AE 36:341)
As soon as…as soon as. Said not once, but twice! The Words of Jesus assuredly bring with them that of which they speak and they do so by virtue of being His own words and so crackling with the power of the Holy Spirit (here you might glimpse a point of intersection between the East and the West!).
Dr. Luther’s conviction, and with him that of the Lutheran Church, is that the Words of Christ accomplish exactly what they say. He certainly knew (as the Formula freely confesses) that it is not the speaking of the pastor per se that effects any of this; the miracle (for it IS a miracle as the analogy with the Incarnation itself shows; see the original context of the passage cited) is rather to be solely attributed to the almighty power of the Words of our Lord Jesus Christ, words He spoke at the first institution of His Supper and that the servants of the Church have repeated faithfully ever since, words alive with the Holy Spirit, words that go on bringing with them exactly what they say. Christ’s body and Christ’s blood. Given for you. Shed for you. For the forgiveness of your sins.
These are, after all, the words of Him who long before said: “Let there be…” “…and there was…”