In Peter’s Pentecost sermon, Peter tells the assembled crowd, “Repent and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins, and you will receive the gift of the Holy Spirit.” Some Christians have taken this verse to mean that baptism is essential for salvation. If a person repents, but does not get baptized, they are not saved.
Stanley Toussaint, in The Bible Knowledge Commentary , analyzes three different views biblical scholars have proposed for the command to be baptized in Acts 2.
A problem revolves around the command ‘be baptized’ and its connection with the remainder of 2:38. There are several views: (1) One is that both repentance and baptism result in remission of sins. In this view, baptism is essential for salvation. The problem with this interpretation is that elsewhere in Scripture forgiveness of sins is based on faith alone (John 3:16, 36; Rom. 4:1–17; 11:6; Gal. 3:8–9; Eph. 2:8–9; etc.). Furthermore Peter, the same speaker, later promised forgiveness of sins on the basis of faith alone (Acts 5:31; 10:43; 13:38; 26:18).
(2) A second interpretation translates 2:38, ‘Be baptized … on the basis of the remission of your sins.’ The preposition used here is eis which, with the accusative case, may mean ‘on account of, on the basis of.’ It is used in this way in Matthew 3:11; 12:41; and Mark 1:4. Though it is possible for this construction to mean ‘on the basis of,’ this is not its normal meaning; eis with the accusative case usually describes purpose or direction.
(3) A third view takes the clause and be baptized, every one of you, in the name of Jesus Christ as parenthetical. Several factors support this interpretation: (a) The verb makes a distinction between singular and plural verbs and nouns. The verb ‘repent’ is plural and so is the pronoun ‘your’ in the clause so that your sins may be forgiven (lit., ‘unto the remission of your sins,’ eis aphesin tōn hamartiōn hymōn). Therefore the verb ‘repent’ must go with the purpose of forgiveness of sins. On the other hand the imperative ‘be baptized’ is singular, setting it off from the rest of the sentence. (b) This concept fits with Peter’s proclamation in Acts 10:43 in which the same expression ‘sins may be forgiven’ (aphesin hamartiōn) occurs. There it is granted on the basis of faith alone. (c) In Luke 24:47 and Acts 5:31 the same writer, Luke, indicates that repentance results in remission of sins.
Darrell Bock, in The Gospels and Acts (The Holman Apologetics Commentary on the Bible) , also argues that baptism is not essential to salvation:
Despite later controversy about whether one must believe and be baptized in order to be saved, what Peter says here and in his own later epistle shows that the key is the response to God, not the rite per se. This response and its cleansing effect are what the rite signifies, not what the rite accomplishes. The act of baptism portrays a washing and signifies what faith produces, cleansing. Peter explains this in 1 Peter 3: 21: ‘Baptism, which corresponds to this, now saves you (not the removal of the filth of the flesh, but the pledge of a good conscience toward God) through the resurrection of Jesus Christ.’ The rite is not magical but symbolizes what repentance is asking God to do, to give forgiveness (Acts 5: 31; 10: 43; 13: 38; 26: 18). To undertake baptism is to affirm in public what the heart has privately done to come into relationship with God. ‘Baptism is a natural part of the much more important conversion’ and a ‘self-evident expression of conversion’ (Schweizer, TDNT 6: 413– 14). Thus, baptism is the representation of the cleansing that belongs to salvation.