"Could you comment on the following work of Luther where he states that salvation comes by baptism. Luther stated in his large Catechism 1529 used to aid clergy: "But I am baptized! And if I am baptized, I have the promise that I shall be saved and have eternal life, both in soul and body." ... No greater jewel, therefore, can adorn our body and soul than Baptism, for through it we obtain perfect holiness and salvation, which no other kind of life and no work on earth can acquire"[source].Sure. Keep in mind though, I'm not a Lutheran, so while I can explain his view of baptism, this doesn't mean I hold to Luther's view of baptism.
The quote you've posted is from the end of Luther's exposition of baptism in his Large Catechism. That is, it's part of the conclusion of his previous argumentation. This section of the Large Catechism is a fairly easy read for anyone interested in Luther's view on this subject.
My basic explanation of Luther's view is thus: Luther held the sacraments are a form of the Word of God. Luther believed that the Word of God was oral, written, and sacramental. The Word comes to change our hearts, minds, reason, and will. If one is baptized in faith, they have received one of the promises that God will be their savior. It is His promise to us that he will save those with faith. Luther held that Word of promise is the power of God unto salvation, not works of penance like the Romanists of his day popularly held. Baptism establishes that we are children of God. Luther argued that the validity of the promise does not rest on faith. Faith is simply the response. It grasps and makes use of the benefits, but the promise of God is there. Christ saves, not faith. Faith only receives the salvation Christ gives. Luther believed that God, through the power of His Word, establishes the relationship with His people.
If you read through the link to the Catechism (I've provided above), you'll notice Luther places a heavy emphasis on Mark 16:16, "He that believeth and is baptized shall be saved; but he that believeth not shall be." So, with the quote you've asked me about, Luther is using baptism as an assurance of salvation, or holding God to His Word. He says in the Catechism,
"...since we now know what Baptism is and how it is to be regarded, we must also learn for what purpose it was instituted, that is, what benefits, gifts, and effects it brings. Nor can we understand this better than from the words of Christ quoted above, “He who believes and is baptized shall be saved.” To put it most simply, the power, effect, benefit, fruit, and purpose of Baptism is to save. No one is baptized in order to become a prince, but as the words say, to “be saved.” To be saved, we know, is nothing else than to be delivered from sin, death and the devil and to enter into the kingdom of Christ and live with him forever."He then states,
Our know-it-alls, the new spirits, assert that faith alone saves and that works and external things contribute nothing to this end. We answer: It is true, nothing that is in us does it but faith, as we shall hear later on. but these leaders of the blind are unwilling to see that faith must have something to believe — something to which it may cling and upon which it may stand. Thus faith clings to the water and believes it to be Baptism in which there is sheer salvation and life, not through the water, as we have sufficiently stated, but through its incorporation with God’s Word and ordinance and the joining of his name to it. When I believe this, what else is it but believing in God as the one who has implanted his Word in this external ordinance and offered it to us so that we may grasp the treasure it contains?Baptism is God's Word and God's Promise. According to Luther it is God's work:
Without faith Baptism is of no use, although in itself it is an infinite, divine treasure. So this single expression, “He who believes,” is so potent that it excludes and rejects all works that we may do with the intention of meriting salvation through them. For it is certain that whatever is not faith contributes nothing toward salvation, and receives nothing.According to Luther, when one goes through doubt or struggle, one must cling to God's Word of promise:
However, it is often objected, “If Baptism is itself a work, and you say that works are of no use for salvation, what becomes of faith?” To this you may answer: Yes, it is true that our works are of no use for salvation. Baptism, however, is not our work but God’s (for, as was said, you must distinguish Christ’s Baptism quite clearly from a bath-keeper’s baptism). God’s works, however, are salutary and necessary for salvation, and they do not exclude but rather demand faith, for without faith they could not be grasped. Just by allowing the water to be poured over you, you do not receive Baptism in such a manner that it does you any good. But it becomes beneficial to you if you accept it as God’s command and ordinance, so that, baptized in the name of God, you may receive in the water the promised salvation. This the hand cannot do, nor the body, but the heart must believe it.
To appreciate and use Baptism aright, we must draw strength and comfort from it when our sins or conscience oppress us, and we must retort, “But I am baptized! And if I am baptized, I have the promise that I shall be saved and have eternal life, both in soul and body.” This is the reason why these two things are done in Baptism: the body has water poured over it, though it cannot receive anything but the water, and meanwhile the Word is spoken so that the soul may grasp it.