On the Catechism . . .
As we come to the end of the Church Year and its emphasis on the end times, our Catechism focus is on the Lord's Supper - the gift of God which gives us forgiveness and strength of faith to endure these times, and which is also our "foretaste of the feast to come."
What is the Sacrament of the Altar?
It is the true body and blood of our Lord Jesus Christ under the bread and wine, instituted by Christ Himself for us Christians to eat and to drink.
Where is this written?
The holy Evangelists Matthew, Mark, Luke, and St. Paul write: Our Lord Jesus Christ, on the night when He was betrayed, took bread, and when He had given thanks, He broke it and gave it to the disciples and said: "Take, eat; this is My body, which is given for you. This do in remembrance of Me." In the same way also He took the cup after supper, and when He had given thanks, He gave it to them, saying: "Drink of it, all of you; this cup is the new testament in My blood, which is shed for you for the forgiveness of sins. This do, as often as you drink it, in remembrance of Me."
Just as we have said that Baptism is not simple water, so here also we say that though the Sacrament is bread and wine, it is not mere bread and wine, such as are ordinarily served at the table [1 Cor 10:16-17]. But this is bread and wine included in, and connected with, God's Word.
It is the Word, I say, that makes and sets this Sacrament apart. So it is not mere bread and wine, but is, and is called, Christ's body and blood [1 Cor 11:23-27]. For it is said, "When the Word is joined to the element or natural substance, it becomes a Sacrament." . . . The Word must make a Sacrament out of the element, or else it remains a mere element. Now, it is not the word or ordinance of a prince or emperor. But it is the Word of the grand Majesty, at whose feet all creatures should fall and affirm it is as He says, and accept it with all reverence, fear, and humility [Isaiah 45:23; Philippians 2:10].
(from The Large Catechism: The Sacrament of the Altar §9-11
in Concordia: The Lutheran Confessions (first edition), © 2005 CPH, p 458)