1 Peter 3:15-22
15 But sanctify the Lord God in your hearts: and be ready always to give an answer to every man that asketh you a reason of the hope that is in you with meekness and fear:
16 Having a good conscience; that, whereas they speak evil of you, as of evildoers, they may be ashamed that falsely accuse your good conversation in Christ.
17 For it is better, if the will of God be so, that ye suffer for well doing, than for evil doing.
18 For Christ also hath once suffered for sins, the just for the unjust, that he might bring us to God, being put to death in the flesh, but quickened by the Spirit:
19 By which also he went and preached unto the spirits in prison;
20 Which sometime were disobedient, when once the longsuffering of God waited in the days of Noah, while the ark was a preparing, wherein few, that is, eight souls were saved by water.
21 The like figure whereunto even baptism doth also now save us (not the putting away of the filth of the flesh, but the answer of a good conscience toward God,) by the resurrection of Jesus Christ:
22 Who is gone into heaven, and is on the right hand of God; angels and authorities and powers being made subject unto him.
The Grace New Testament Commentary - 1 Peter 3:21
3:21 By saying not the removal of the filth of the flesh, Peter is clarifying that water baptism is not what saves. He rejects the idea of water baptism as a requirement for salvation. Baptism is the antitype of the ark, not the Flood. It saves the believer from judgment. Many take this as a reference to salvation from sin in justification. The statement, the answer of a good conscience toward God seems to support this. But the question is how were Peter's readers being saved in their present experience, since he says baptism now saves you?
This reference to baptism and that of Acts 2:38 are applicable to the first-century generation of Jews who were converting to Christianity. The judgment in view is that of Titus's attack on Judah and the fiery judgment coming on the generation of Jews who rejected Jesus. If they hear Peter's message and identify with Christ, they are separating themselves from their generation. Therefore water baptism saves from temporal, corporal punishment. The punishment in 1 Pet 3:19-20 looks at the physical, temporal judgment Noah's generation underwent in the Flood, with only those identifying with (entering) the ark surviving. In the same way the readers' failure to identify with Christ for fear of persecution would only lead to identification with Judah in the hour of her punishment from God in AD 66-70.
This does justice to the issue of testimony under adversity in which the readers are asked to give an account of the hope they have (v 15). The Christian's public testimony begins with water baptism, which is a picture of spirit baptism. For Peter's readers it separated them from the Jewish community that was facing God's coming judgment. The significance of baptism here is identification with Christ and therefore the Church, the body of Christ.
Peter also emphasizes the resurrection of Jesus Christ, through which believers are saved. The resurrection of Jesus is a crucial element of our faith. In context, as Peter has been talking about deliverance from temporal, corporal punishment, this reminder is that even if some die in persecution, they will be raised to new life just as Jesus was.
Charles Bing - Grace, Salvation, and Discipleship - Baptism Saves Us, 1 Peter 3:21
(Salvation) Interpretation: Water baptism saves unbelievers from hell.
(Discipleship) Interpretation: Spirit baptism saves believers from a guilty conscience or from the Tribulation judgments.
Second (Discipleship) Interpretation: Water baptism saves Jewish believers from temporal judgment.
This is a notoriously difficult passage to understand. It has been used as (a Salvation verse) by those who believe in baptismal regeneration. That view can be dismissed on theological grounds and the interpretive principle that unclear passages (of which this is certainly one) should be interpreted in light of clear passages. Nothing could be clearer than the New Testament teaching that salvation is by grace through faith alone, not by anything we do. Besides, the phrase "now saves us" emphasizes the present experience of the readers.
One way of interpreting this passage as (pertaining to Discipleship) sees only Spirit baptism, not water baptism. It is noted that the phrase "not the removal of filth from the flesh" and the mention that the baptism is "through the resurrection of Jesus Christ" both exclude water. The context does mention the work of the Holy Spirit in resurrecting Jesus Christ (1 Peter 3:18). Romans 6:3-5 teaches that Spirit baptism unites us with Christ in His resurrection. This reminds also of 1 Corinthians 12:13: "For by one Spirit we were all baptized into one body - whether Jews or Greeks, whether slaves or free - and have all been made to drink into one Spirit." United with Christ in His body, believers are safe from danger, like Noah and his family were safe in the ark (3:20). That is how baptism is the "antitype" (the fulfillment of a corresponding earlier type) for the ark.
But what danger are the readers saved from? One answer is that they are saved from a guilty conscience in the present. When believers are justified and baptized by the Spirit into the body of Christ, they are also forgiven all their sins positionally (Col. 2:13). The new position in Christ also puts them in a position to have fellowship forgiveness when they sin as Christians. By walking in forgiveness, believers maintain a clear conscience. Another interpretation of this salvation is that Peter is assuring the readers that they will be saved from the future trouble of the Tribulation. The ark saved Noah's family from God's watery wrath, so Spirit baptism that places believers safely in Christ will save them from the Tribulation coming upon the world. This would look forward to the Rapture which saves believers from the wrath of the Tribulation (1 Thess. 1:10; 5:1-11). Against this latter view is the phrase "now saves us" which indicates a present benefit, not a future one.
A second (Discipleship) interpretation takes the baptism as water baptism and gives it the same significance as how baptism is viewed in Acts 2:38. Baptism would separate Peter's first-century Jewish readers from their evil generation and identify them instead with the new Christian community so that they would be saved from the temporal corporal judgment coming upon Israel for their terrible sin of crucifying Christ. That destruction came upon Jerusalem through the Romans in A.D. 70. They would receive forgiveness for that sin and thus a good conscience. The resurrection of Christ is mentioned as an encouragement to individual believers who might die in the coming destruction that they also will be raised.
We cannot resolve the interpretation of this passage easily. The argument seems strongest that this is a Spirit baptism that has the present benefit of saving us from a guilty conscience. One thing that is clear is that this passage does not make baptism a condition for eternal salvation. The salvation spoken of is clearly for believers, and thus clearly (Discipleship).