However, not all proponents of baptismal regeneration see baptism as a shortcut to salvation or a quick fix to the problem of sin. Many view it as a necessary element—in addition to repentance and faith—that completes the work of salvation. And as a proof text, they point to Peter's words in Acts 2:38, "Peter said to them, 'Repent, and each of you be baptized in the name of Jesus Christ for the forgiveness of your sins; and you will receive the gift of the Holy Spirit'" (emphasis added).
By calling on each of them to "be baptized in the name of Jesus Christ" Peter does not allow for any "secret disciples" (cf. Matthew 10:32-33). Baptism would mark a public break with Judaism and identification with Jesus Christ. Such a drastic public act would help weed out any conversions which were not genuine. In sharp contrast to many modern gospel presentations, Peter made accepting Christ difficult, not easy. By so doing, he followed the example of our Lord Himself (Luke 14:26-33; 18:18-27). Baptism was always "in the name of Jesus Christ." That was the crucial identification, and the cost was high for such a confession.  John MacArthur, The MacArthur New Testament Commentary: Acts 1-12 (Chicago: Moody Press, 1994), 73.
[Baptismal regeneration] ignores the immediate context of the passage. As already noted, baptism would be a dramatic step for Peter's hearers. By publicly identifying themselves as followers of Jesus of Nazareth, they risked becoming outcasts in their society (cf. John 9:22). Peter calls upon them to prove the genuineness of their repentance by submitting to public baptism. In much the same way, our Lord called upon the rich young ruler to prove the genuineness of his repentance by parting with his wealth (Luke 18:18-27). Surely, however, no one would argue from the latter passage that giving away one's possessions is necessary for salvation. Salvation is not a matter of either water or economics. True repentance, however, will inevitably manifest itself in total submission to the Lord's will.  The MacArthur New Testament Commentary: Acts 1-12, 73-74.
Even Christ Himself—in perhaps His most famous quote—denied the need for works to accomplish salvation: "For God so loved the world that He gave His only begotten Son, that whosoever believes in Him shall not perish, but have eternal life" (John 3:16). In fact, the need for baptism would contradict the entirety of Christ's ministry. As John MacArthur puts it, "After condemning the ritualistic religion of the scribes and Pharisees, our Lord would hardly have instituted one of His own."  The MacArthur New Testament Commentary: Acts 1-12, 74.
This interpretation is not true to the facts of Scripture. Throughout the book of Acts, forgiveness is linked to repentance, not baptism (cf. Acts 3:19; 5:31; 26:20). In addition, the Bible records that some who were baptized were not saved (Acts 8:13, 21-23), while some were saved with no mention of their being baptized (Luke 7:37-50; Matthew 9:2; Luke 18:13-14). The story of the conversion of Cornelius and his friends very clearly shows the relationship of baptism to salvation. It was only after they were saved, as shown by their receiving the Holy Spirit (Acts 10:44-46), that they were baptized (Acts 10:47-48). Indeed, it was because they had received the Spirit (and hence were saved) that Peter ordered them to be baptized (v. 47). That passage clearly shows that baptism follows salvation; it does not cause it.  The MacArthur New Testament Commentary: Acts 1-12, 74.
The order is clear. Repentance is for forgiveness. Baptism follows that forgiveness; it does not cause it (cf. Acts 8:12, 34-39; 10:34-48; 16:31-33). It is the public sign or symbol of what has taken place on the inside. It is an important step of obedience for all believers, and should closely follow conversion. In fact, in the early church it was inseparable from salvation, so that Paul referred to salvation as being related to "one Lord, one faith, one baptism" (Ephesians 4:5).  The MacArthur New Testament Commentary: Acts 1-12, 75.
Just as the Flood immersed all people in the judgment of God, yet some passed through safely, so also his final judgment will involve everyone, but those who are in Christ will pass through securely. The experience of Noah's family in the Flood is also analogous to the experience of everyone who receives salvation. Just as they died to their previous world when they entered the ark and subsequently experienced a resurrection of sorts when they exited the ark to a new post-Flood world, so all Christians die to their old world when they enter the body of Christ (Romans 7:4-6; Galatians 2:19-20; Ephesians 4:20-24). They subsequently enjoy newness of life that culminates one day with the resurrection to eternal life. . . .
Therefore, God provides salvation because a sinner, by faith, is immersed into Christ's death and resurrection and becomes His own through that spiritual union. Salvation does not occur by means of any rite, including water baptism.  John MacArthur, The MacArthur New Testament Commentary: 1 Peter (Chicago: Moody Publishers, 2004) 217-218.