What is Baptism?
Baptism is not just plain water, but it is water contained within God's command and united with God's Word.
Where in the Word of God is this?
Where our Lord Christ spoke in the last chapter of Matthew (Matthew 28:19):
What does Baptism give? What good is it?
It gives us the forgiveness of sins, redeems us from death and the Devil, and gives eternal salvation to all who believe this, just as God's words and promises declare.
What are these words and promises of God?
Our Lord Christ spoke one of them in the last chapter of Mark (Mark 16:16):
How can water do such great things?
Water doesn't make these things happen, of course. It is God's Word, which is with and in the water. Because, without God's Word, the water is plain water and not baptism. But with God's Word it is a Baptism, a grace-filled water of life, a bath of new birth in the Holy Spirit, as St. Paul said to Titus in the third chapter (Titus 3:5-8): "Through this bath of rebirth and renewal of the Holy Spirit, which He poured out on us abundantly through Jesus Christ, our Savior, that we, justified by the same grace are made heirs according to the hope of eternal life. This is a faithful saying."
What is the meaning of such a water Baptism?
It means that the old Adam in us should be drowned by daily sorrow and repentance, and die with all sins and evil lusts, and, in turn, a new person daily come forth and rise from death again. He will live forever before God in righteousness and purity.
Where is this written?
St. Paul says to the Romans in Chapter Six (Romans 6:4): "We are buried with Christ through Baptism into death, so that, in the same way Christ is risen from the dead by the glory of the Father, thus also must we walk in a new life."