Luke 3:2-17
2 Annas and Caiaphas being the high priests, the word of God came unto John the son of Zacharias in the wilderness.
3 And he came into all the country about Jordan, preaching the baptism of repentance for the remission of sins;
4 As it is written in the book of the words of Esaias the prophet, saying, The voice of one crying in the wilderness, Prepare ye the way of the Lord, make his paths straight.
5 Every valley shall be filled, and every mountain and hill shall be brought low; and the crooked shall be made straight, and the rough ways shall be made smooth;
6 And all flesh shall see the salvation of God.
7 Then said he to the multitude that came forth to be baptized of him, O generation of vipers, who hath warned you to flee from the wrath to come?
8 Bring forth therefore fruits worthy of repentance, and begin not to say within yourselves, We have Abraham to our father: for I say unto you, That God is able of these stones to raise up children unto Abraham.
9 And now also the axe is laid unto the root of the trees: every tree therefore which bringeth not forth good fruit is hewn down, and cast into the fire.
10 And the people asked him, saying, What shall we do then?
11 He answereth and saith unto them, He that hath two coats, let him impart to him that hath none; and he that hath meat, let him do likewise.
12 Then came also publicans to be baptized, and said unto him, Master, what shall we do?
13 And he said unto them, Exact no more than that which is appointed you.
14 And the soldiers likewise demanded of him, saying, And what shall we do? And he said unto them, Do violence to no man, neither accuse any falsely; and be content with your wages.
15 And as the people were in expectation, and all men mused in their hearts of John, whether he were the Christ, or not;
16 John answered, saying unto them all, I indeed baptize you with water; but one mightier than I cometh, the latchet of whose shoes I am not worthy to unloose: he shall baptize you with the Holy Ghost and with fire:
17 Whose fan is in his hand, and he will throughly purge his floor, and will gather the wheat into his garner; but the chaff he will burn with fire unquenchable.
The Grace New Testament Commentary - Luke 3:3
3:3 John ministered in all the region of the Jordan. The nation of Israel needed to reestablish its fellowship with God. The public act of water baptism pictured a renewed allegiance to God and a confession of past waywardness. This act of repentance resulted in forgiveness of sins, which refers to cleansing and restored fellowship. Repentance and the symbolic baptism did not confer eternal life or justification - only belief in Jesus can grant this as John 3:16-18; 5:24-25; 6:47; 11:25-27; 20:30-31 clearly teach. However, in a similar manner in which 2 Chronicles 7 called the nation (composed of believers and non-believers) to repentance as a condition for fellowship with God on a national scale, John likewise did this in preparation for the appearance of Jesus, the awaited Messiah.
Charles Bing - Grace, Salvation, and Discipleship - John's Baptism of Repentance, Matthew 3:1-12 (cf. Luke 3:3-17)
(Salvation) Interpretation: John the Baptist baptized unbelievers who repented of sins and changed their conduct so that they would be saved.
(Discipleship) Interpretation: John the Baptist baptized Jews who wanted to show their repentance under the Mosaic Covenant, separate from sinful Israel, and prepare for the coming Messiah.
This is a passage where it is important to understand the setting and context. John the Baptist has a message for the nation of Israel about repentance and baptism. But is he telling them as well as people today how to be saved?
At the time that John preached, the nation of Israel was still under the Mosaic Covenant. For God's covenant people, the way to be restored from departing from God was to repent - to change their minds or attitudes about their sin (Deut. 30:2, 10: 2 Chr. 7:14). At that point, they are prepared to receive the Messiah that John would introduce. His baptism was a witness to their repentance and anticipation of the Messiah. The works he tells the Pharisees, Sadducees, and others to do (Matt. 3:7-9; Luke 3:7-14) are works that are consistent with true repentance, not works that will save them. This passage clearly differentiates between repentance as an inner attitude and "fruits worthy of repentance" which is the outer conduct (v. 8).
It helps to see what the apostle Paul says about John's baptism in Acts 19:4. Speaking to Ephesians who had received John's baptism but had not believed in Jesus Christ, he said, "John indeed baptized with a baptism of repentance, saying to the people that they should believe on Him who would come after him, that is, on Jesus Christ." Those who had received John's baptism were Jewish believers who needed to become Christians through faith in Jesus Christ. They were in the transition period between the era of Law and the era of grace.
As recorded in Acts 13:24, Paul said in Pisidian Antioch before Christ officially presented Himself to Israel as the Messiah, that John preached "the baptism of repentance to all the people of Israel." If we understand the Jewish audience and the covenantal background for John's preaching of baptism and repentance, we should not make this a template for preaching the gospel in the church age. First, this does not at all speak of Christian baptism. Second, repentance does not save anyone in and of itself, but the change of heart that it reflects is well prepared to believe in the Savior. Though it addresses God's people under His covenant, we can learn from this as a general (Discipleship message) that teaches the way back to God begins with a change of mind and heart.