The Sacrament is not founded upon people's holiness, but upon God's Word...

For the Sacrament is not founded upon people's holiness, but upon God's Word.  Just as no saint on earth, indeed, no angel in heaven, can make bread and wine be Christ's body and blood, so also no one can change or alter it, even though it is misused.  The Word by which it became a Sacrament and was instituted does not become false because of the person or his unbelief.  For Christ does not say, "If you believe or are worthy, you receive My body and blood." No, He says, "Take, eat and drink; this is My body and blood." Likewise, He says, "Do this" (i.e., what I now do, institute, give, and ask you, take).  That is like saying, "No matter whether you are worthy or unworthy, you have here His body and blood by virtue of these words that are added to the bread and wind."  Note and remember this well.  For upon these words rest all our foundation, protection, and defense against all errors and deception that have ever come or may yet come.
~BOC, LC, V, 16-19

The Word makes the Sacrament...

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.  For it is said, "When the Word is joined to the element or natural substance, it becomes as Sacrament."  This saying of St. Augustine is so properly and so well put that he has scarcely said anything better.  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 as He says, and accept it with all reverence, fear, and humility.
~BOC, LC, V, 10-11

A truly Christian life is nothing other than a daily Baptism...

Lastly, we must also know what Baptism signifies and why God has ordained just this outward sign and ceremony for the Sacrament by which we are first received into the Christian Church.  The act or ceremony is this: we are sunk under the water, which passes over us, and afterward are drawn out again.  These two parts, (a) to be sunk under the water and (b) drawn out again, signify Baptism's power and work.  It is nothing other than putting to death the old Adam and affecting the new man's resurrection after that.  Both of these things must take place in us all our lives.  So, a truly Christian life is nothing other than a daily Baptism, once begun and ever to be continued.  For this must be done without ceasing, that we always keep purging away whatever belongs to the old Adam.  Then what belongs to the new man may come forth.

~BOC, LC, IV, 64-65

Baptism, as with the entire Gospel, is an outward, verbal preaching...

Now these "new spirits" are so crazy that they separate faith and the object to which faith clings and is bound, even if it is something outward.  Yes, it shall and must be something outward, so that it may be grasped by our senses and understood, and by them be brought into the heart.  For indeed, the entire Gospel is an outward, verbal preaching.  In short, what God does and works in us He intends to work through such outward ordinances.  Therefore, wherever He speaks--indeed, no matter what direction or by whatever means He speaks--faith must look there.  It must hold to that object.  Now here we have the words "Whoever believes and is baptized will be saved" (Mark 16:16).  What else can these words refer to but Baptism, that is, to the water included in God's ordinance?  Therefore, it makes sense that whoever rejects Baptism rejects God's Word, faith, and Christ, who directs us to Baptism and binds us to Baptism.
~BOC, LC, IV, 30-31

Baptism gives faith the outward thing upon which it stands and rests...

Our would-be "wise spirits" assert that faith alone saves, and that works and outward things do nothing.  We answer, "It is true, indeed, that nothing in us is of any use but faith, as we shall hear still further."  But these blind guides are unwilling to see this:  faith must have something that it believes, that is, of which it takes hold and upon which it stands and rests.  So faith clings to the water and believes in Baptism, there is pure salvation and life.  This is not through the water (as we have stated well enough), but through the fact that it is embodied in God's Word and institution, and that God's name abides in it.  Now, if I believe this, what else is it than believing in God as the One who has given and planted His Word into this ordinance and offers to us this outward thing by which we may gain such a treasure?
~BOC, LC, IV, 28-29

We are baptized by God Himself...

To be baptized in God's name is to be baptized not by men, but by God Himself.  Therefore, although it is performed by human hands, it is still truly God's own work.
~BOC, LC, IV, 10

Certitude in the promise and immovable Word of the Holy Gospel...

We believe, teach, and confesss that many weaknesses and defects cling to the true believers and truly regenerate, even up to the day they are buried.  Still, they must not on that account doubt either their righteousness, which has been credited to them through faith, or the salvation of their souls.  They must regard it as certain that for Christ' sake, according to the promise and immovable Word of the Holy Gospel, they have a gracious God.
~BOC, FE, III, 9