The Bible directly links baptism to salvation:

• Mark 16:16 “He who believes and is baptized will be saved; but he who does not believe will be condemned.”
• John 3:5 “Jesus answered, ‘I tell you the truth, unless a man is born of water and of the Spirit, he cannot enter the kingdom of God.’” (cf. 3:3: “unless a man is born again …”)
• Acts 2:38-41 “And Peter said to them, ‘Repent, and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins; and you shall receive the gift of the Holy Spirit. For the promise is to you and to your children and to all that are far off, every one whom the Lord our God calls to him.’ And he testified with many other words and exhorted them, saying, ‘Save yourselves from this crooked generation.’ So those who received his word were baptized, and there were added that day about three thousand souls.” (cf. 9:17-18; 1 Corinthians 12:13: both associate the Holy Spirit with baptism)
• Acts 22:16 “And now why do you wait? Rise and be baptized, and wash away your sins, calling on his name.” (cf. 9:17-18)
• Romans 6:3-4 “Or don’t you know that all of us who were baptized into Christ Jesus were baptized into his death? We were therefore buried with him through baptism into death in order that, just as Christ was raised from the dead through the glory of the Father, we too may live a new life.”
• 1 Corinthians 6:11 “And such were some of you. But you were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and in the Spirit of our God.”
• Titus 3:5 “He saved us, not because of deeds done by us in righteousness, but in virtue of his own mercy, by the washing of regeneration and renewal in the Holy Spirit…”
• 1 Peter 3:21 “Baptism … now saves you …”

In Acts 2:38-41 alone we learn that baptism brings: (1) “forgiveness of sins;” (2) the indwelling of the Holy Spirit, which no unregenerate person could possess; (3) salvation (“save yourselves”); and (4) inclusion in the rank of saved “souls” (cf. Galatians 3:27).

Romans 6:3-4 incorporates the blood and redeeming death of Jesus into baptism by referring to his “death.” So also does the larger passage of 1 Peter 3:14-22; 4:1.

St. Peter asserts that “baptism ... saves” us (1 Peter 3:21). If a dispute arises as to whether “baptism saves” us or not, and an inspired Bible passage states “baptism saves,” and Mark 16:16 also asserts that “he who believes and is baptized will be saved” — are those not answers to the very question being asked? How could they be any more plain and obvious than they are?

The larger passage of 1 Peter 3 is very instructive. The Bible often uses natural things as symbols of supernatural ones — for example, Jonah being in the belly of the whale three days and then emerging alive as a symbol of Jesus being dead for three days and then rising; many parables use similar parallelism. 

“Saved” in reference to Noah’s Ark meant physical, wholly-natural “salvation” from drowning. But then Peter uses that as an illustration of the supernatural sacrament of baptism, which “corresponds” to Noah’s Ark as an analogy (the Ark being a natural prototype of a supernatural thing). 

It doesn’t follow that Peter’s saying that this baptism “saves” us is also merely symbolic. Peter doesn’t say that! He throws in the fact that this baptism was not merely “a removal of dirt from the body” (not merely a physical, natural thing), but related to suffering with (3:14, 16-17; 4:1) and being resurrected with Christ (3:21), just as St. Paul also taught (even more explicitly) in Romans 6:3-4.

Throughout the New Testament, baptism is seen as imperative and the means by which the early Church would know who was part of their fold or not. This was true for Paul (Acts 22:16; cf. 9:17-18). As soon as he was “persuaded” of Christianity, the first thing he did was get baptized, which in turn washed away his sins.

• Acts 8:12-13 “But when they believed Philip as he preached good news about the kingdom of God and the name of Jesus Christ, they were baptized, both men and women. Even Simon himself believed, and after being baptized he continued with Philip. ...”
• Acts 8:34-38 “And the eunuch said to Philip, ‘About whom, pray, does the prophet say this, about himself or about some one else?’ Then Philip opened his mouth, and beginning with this scripture he told him the good news of Jesus. And as they went along the road they came to some water, and the eunuch said, ‘See, here is water! What is to prevent my being baptized?’ And he commanded the chariot to stop, and they both went down into the water, Philip and the eunuch, and he baptized him.”

The baptism of entire “households” also strongly implies infant baptism:

• Acts 16:14-15 “One who heard us was a woman named Lydia, from the city of Thyati’ra, a seller of purple goods, who was a worshiper of God. The Lord opened her heart to give heed to what was said by Paul. And when she was baptized, with her household ...”
• Acts 16:32-33 “And they spoke the word of the Lord to him and to all that were in his house. And he took them the same hour of the night, and washed their wounds, and he was baptized at once, with all his family.”
• Acts 18:8 “Crispus, the ruler of the synagogue, believed in the Lord, together with all his household; and many of the Corinthians hearing Paul believed and were baptized.”
• 1 Corinthians 1:16 “I did baptize also the household of Steph’anas. ...”