(I Peter 3:21 (Includes: Rom. 6:4))

First let us see what it may mean, and then what it cannot mean.

Actually, there is a baptism which saves us -- not our baptism which took place at Calvary almost 2000 years ago.  Christ's death was a baptism.  He was baptized in the waters of judgment.  This is what He meant when He said, "I have a baptism to be baptized with, and how distressed I am till it is accomplished!" (Luke 12:50).  The psalmist described this baptism in the words, "Deep calls unto deep at the noise of Your waterfalls; all Your waves and billows have gone over me" (Ps. 42:7).  In His death, Christ was baptized in the waves and billows of God's wrath, and it is this baptism that is the basis for our salvation.

But we must accept His death for ourselves.  Just as Noah and his family had to enter the ark to be saved, so we must commit ourselves to the Lord as our only Savior.  When we do this, we become identified with Him in His death, burial, and resurrection.  In a very real sense, we then have been crucified with Him (Gal. 2:20), we have been buried with Him (Rom. 6:4), and we have been brought from death to life with Him (Rom.6:4).

All this is pictured in the believer's baptism.  The ceremony is an outward sign of what has taken place spiritually; we have been baptized into Christ's death.  As we go under the water, we acknowledge that we have been buried with Him.  As we come up out of the water, we show that we have risen with Him and want to walk in newness of life.

An antitype which now saves us-- baptism refers to Christ's baptism unto death on the cross and our identification with Him in it, which water baptism represents.

The verse cannot mean that we are saved by ritual baptism in water for the following reasons:

1. That would make water the savior, instead of the Lord Jesus.  But He said, "I am the way" (John 14:6).
2. It would imply that Christ died in vain.  If people can be saved by water, then why did the Lord Jesus have to die?
3. It simply doesn't work.  Many who have been baptized have proved by their subsequent lives that they were never truly born again.
Neither can this verse mean that we are saved by faith in baptism.

1. This would mean that the Savior's work on the cross was not sufficient.  When He cried, "It is finished," it wasn't really so, according to this view, because baptism must be added to that work for salvation.
2.  If baptism is necessary for salvation, it is strange that the Lord did not personally baptize anyone.  John 4:1,2 states that Jesus did not do the actual baptizing of His followers; His disciples did this.
3.  The Apostle Paul thanked God that he baptized very few of the Corinthians (I Cor. 1:14-16).  This would be strange thanksgiving for an evangelist if baptism were essential for salvation!  The fact that Paul did baptize some shows that he taught believer's baptism, but the fact that he baptized only a few shows that he did not consider it a requirement for salvation.
4.  The penitent thief on the cross was not baptized, yet he was assured of being in Paradise with Christ (Luke 23:43).
5. The Gentiles who were saved in Caesarea received the Holy Spirit when they believed (Acts 10:44), showing that they then belonged to Christ (Rom.8:9b).  After receiving the Holy Spirit, that is, after being saved, they were baptized  (vv.47, 48).  Therefore, baptism was not necessary for their salvation.  They were saved first, then baptized in water.
6.  In the NT, baptism is always connected with death and not with spiritual birth.
7.  There are about 150 passages in the NT which teach that salvation is by faith alone.  These cannot be contradicted by two or three verses that seem to teach that baptism is necessary for salvation.

Therefore, when we read in verse 21,  Baptism…which now saves us, it does not mean our baptism in literal water, but Christ's baptism unto death and our identification with Him in it.

Not the removal of the filth of the flesh.   The ceremonial worship of the OT, with which Peter's Jewish-Christian readers were familiar, provided a sort of external cleansing.  But it was not able to give the priests or the people a clear conscience with regard to sin.  The baptism of which Peter is speaking is not a question of physical or even of ritual cleansing from defilement.  Water does have the effect of removing dirt from the body, but it cannot provide a good conscience toward God.  Only personal association with Christ in His death, burial, and resurrection can do that.

But the answer of a good conscience toward God.  The question inevitably arises, "How can I have a righteous standing before God?  How can I have a clear conscience before Him?"  The answer is found in the baptism of which Peter has been speaking--Christ's baptism unto death at Calvary and one's personal acceptance of that work.  By Christ's death the Sin question was settled once for all.

Through the resurrection of Jesus Christ.  How do I know that God is satisfied?  I know because He raised Christ from the dead.  A clear conscience is inseparably linked with 2;  they stand or fall together.  The resurrection tells me that God is fully satisfied with the redemptive work of His Son.  If Christ had not risen, we could never be sure that our sins had been put away.  He would have died like any other man.  But the risen Christ is our absolute assurance that the claims of God against our sins have been fully met.

So it now saves us -- baptism…the answer of a good conscience toward God, through the resurrection of Jesus Christ.  My only claim for a good conscience is based on the death, burial, and resurrection of the Lord Jesus Christ.  The order is as follows:

1. Christ was baptized unto death for me at Calvary.
2. When I trust Him as Lord and Savior, I am spiritually united with Him in His death, burial, and resurrection.
3.  Through the knowledge that He has risen, my request for a clear conscience is answered.
4.  In water baptism, I give visible expression to the spiritual deliverance I have experienced.
 

Mark 16:16

Verse 16 is used by some to teach the necessity of water baptism for salvation.  We know it cannot mean that for the things cited above in I Peter 3:21. 

Approximately 150 passages in the NT state that salvation is by faith alone. No verse or few verses could contradict this overwhelming testimony.

Baptism is connected with death and burial in the NT, not with spiritual birth.  What then does verse 16 mean?  We believe it mentions baptism as the expected outward expression of belief.  Baptism is not a condition of salvation,  but an outward proclamation that the person has been saved.
 

Acts 2 : 37,38

In verse 36: This Jesus, whom you crucified;   They had crucified God's Anointed One, and the coming of the Holy Spirit was evidence that Jesus had been exalted in heaven (see John 7:39).
So mighty was the convicting power of the Holy Spirit that there was an immediate response from the audience.  Without any invitation or appeal from Peter, they cried out, "What shall we do?"  The question was prompted by a deep sense of guilt.  They now realized that the Jesus whom they had slain was God's beloved Son!  This Jesus had been raised from the dead and was now exalted in heaven.  This being so, how could these guilty murderers possibly escape judgment?

v. 38,  Peter's answer was that they should repent and be baptized in the name of Jesus Christ for the remission of sins.  First, they were to repent, acknowledging their guilt, and taking sides with God against themselves.

Then they were to be baptized for (or unto) the remission of their sins.   At first glance, this verse seems to teach salvation by baptism, and many people insist that this is precisely what it does mean.  Such an interpretation is impossible for the following reasons:

1.  In dozens of NT passages, salvation is said to be by faith in the Lord Jesus Christ (John 1:12; 3:16, 36; 6:47; Acts 16:31; Rom. 10:9, for example).
No one verse or two could conceivably contradict such overwhelming testimony.
2. The thief on the cross had the assurance of salvation apart from baptism (Luke 23:43.
3.  The Savior is not stated to have baptized anyone, a strange omission if baptism is essential to salvation.
4.  The Apostle Paul was thankful that he baptized only a few of the Corinthians (I Cor. 1:14-16).
It is important to notice that only Jews were ever told to be baptized for the forgiveness of sins (see Acts 22:16).  In this fact, we believe, is the secret to the understanding of this passage.  The nation of Israel had crucified the Lord of  glory.  The Jewish people had cried out, "His blood be on us and on our children" (Matt. 27:25).  The guilt of the Messiah's death was thus claimed by the people of Israel.
Now, some of these Jews had come to realize their mistake.  By repentance they acknowledged their sin to God.  By trusting the Lord Jesus as their Savior they were regenerated and received eternal forgiveness of sins.  By public water baptism they dissociated themselves from the nation that crucified the Lord and identified themselves with Him.  Baptism thus became the outward sign that their sin in connection with the rejection of Christ (as well as all their sins) had been washed away.  It took them off Jewish ground and placed them on Christian ground.  But baptism did not save them.  Only faith in Christ could do that.  To teach otherwise is to teach another gospel (as in a works salvation) and thus be accursed  (Gal. 1:8,9)

An alternative interpretation of baptism for the remission sins is give by 
Ryrie:
  This does not mean in order that sins might be remitted, for everywhere in the New Testament sins are forgiven as a result of faith in Christ, not as a result of  baptism.  It means be baptized because of the remission of sins.  The Greek preposition eis, for, has this meaning "because of" not only here but also in such a passage as Matthew 12:41 where the meaning can only be "they repented because of (not in order to) the preaching of Jonah."  Repentance brought the remission of sins, and because of the remission sins they were asked to be baptized".

Peter assured them that if they repented and were baptized, they would receive the gift of the Holy Spirit.  To insist that this order applies to us today is to misunderstand God's administrative dealings in the early days of the church.  There are four communities of believers in the book of Acts, and the order of events in connection with the reception of the Holy Spirit is different in each case. 

Here in Acts 2:38 we read about Jewish Christians.  For them, the order was:
1. Repentance
2. Water Baptism
3. Reception of the Holy Spirit.

The conversion of Samaritans is recorded in Acts 8:14-17.  There we read that the following events occurred:
1. They believed
2.  They were baptized in water
3.  The apostles prayed for them
4. The apostles laid their hands on them
5.  They received the Holy Spirit

In Acts 10:44-48 the conversion of Gentiles is in view.  Notice the order here:
1. Faith
2.  Reception of the Holy Spirit
3.  Water Baptism

A final community of believers is made up of disciples of John the Baptist, Act 19:1-7:
1. They believed
2. They were baptized
3. The Apostle Paul laid his hands on them
4.  They received the Holy Spirit

Does this mean there were four ways of salvation in the Book of Acts?  Of course not.  Salvation was, is, and always will be on the basis of faith in the Lord Jesus Christ.  But during the transition period recorded in Acts, God chose to vary the events connected with the reception of the Holy Spirit for reasons which He knew but did not choose to reveal to us.
Then which of these patterns applies to us today?  Since Israel nationally has rejected the Messiah, the Jewish people have forfeited any special privileges they might have had.  Today God is calling out of the Gentiles a people for His Name (Acts 15:14).  Therefore, the order for today is that which is found in Acts 10:
Faith
Reception of the Holy Spirit
Water Baptism

We believe this order applies to all today, to Jews as well as to Gentiles.  This may sound arbitrary at first.  It might be asked, "When did the order in Acts 2:38 cease to apply to Jews and the order in Acts 10:44-48 begin?"
No definite date can be given, of course.  But the Book of Acts traces a gradual transition from the gospel's going out primarily to Jews, to its being repeatedly rejected by the Jews, to its going out to the Gentiles.  By the end of the Book of Acts the nation of Israel had been largely set aside.  By unbelief it had forfeited any special claim as God's chosen people.  During the Church Age it would be reckoned with the Gentile nations, and God's order for the Gentiles, outlined in Acts 10:44-48, would apply.