It's been a while, and the online version seems somewhat different from the one I read at my in-laws (a Lutheran family) -- most of the sections (such as infant baptism) have no scripture at all (there must be other versions, because I recall seeing scripture references in the catechism I read) but a couple of obvious ones that jump out from the online version for the few that seem to have scripture references:
What does Baptism give?
II. Q. What does Baptism give? What good is it?
A. 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.
Q. What are these words and promises of God?
A. Our Lord Christ spoke one of them in the last chapter of Mark (Mark 16:16):
“Whoever believes and is baptized will be saved; but whoever does not believe will be damned.”
I believe in baptism, but this verse doesn't necessarily teach that baptism does all those things --- belief and baptism (the belief and obedience through baptism together, not baptism itself necessarily) save. The Catechism suggests that it is the baptism itself and one's belief in the efficacy of the power of baptism that does the forgiveness and redemption and salvation.
Q. What is confession?
A. Confession has two parts:
First, a person admits his sin
Second, a person receives absolution or forgiveness from the confessor, as if from God Himself, without doubting it, but believing firmly that his sins are forgiven by God in Heaven through it.
funny - no citation -- where is repentance? The confessor gives absolution/forgiveness? I see why they add no scripture.
III. Q. How can water do such great things?
A. 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.”
Titus doesn't say anything about this relationship between simple water and water coupled with God's Word.