John the Baptist prepares the way
1 In those days John the Baptist came preaching in the wilderness of Judea,
2 "Repent, for the kingdom of heaven is at hand."
Repent: Μετανοεῖτε Metanoeite G3340; From μετανοέω metanoeó (met-an-o-eh'-o); to change one's mind or purpose; change the inner man, particularly with reference to acceptance of the will of God. https://biblehub.com/greek/3340.htm
Kingdom of Heaven: βασιλεία τῶν οὐρανῶν; basileia tōn ouranōn; G932 G3588 G3722. Can also be translated Kingdom from Heaven. This term is unique to Matthew. It is used 31 times in this book. Synonymous with the Kingdom of God which is used only 5 times in this book, but more widely used by every other NT writer.
3 For this is he who was spoken of by the prophet Isaiah when he said, "The voice of one crying in the wilderness: Prepare the way of the Lord; make his paths straight."
4 Now John wore a garment of camel's hair and a leather belt around his waist, and his food was locusts and wild honey.
Even today, we consider honey good to eat, and wild honey even better, but locusts probably aren't on our list of delicacies. However, in the OT food laws, God deemed some insects, including locusts, good to eat (Leviticus 11:20-23).
5 Then Jerusalem and all Judea and all the region about the Jordan were going out to him,
6 and they were baptized by him in the river Jordan, confessing their sins.
Though today the word baptism generally evokes thoughts of identifying with Christ’s death, burial, and resurrection, baptism did not begin with Christians. For years before Christ, the Jews had used baptism in ritual cleansing ceremonies of Gentile proselytes. John the Baptist took baptism and applied it to the Jews themselves—it wasn’t just the Gentiles who needed cleansing. https://www.gotquestions.org/baptism-of-John.html
7 But when he saw many of the Pharisees and Sadducees coming for baptism, he said to them, "You brood of vipers! Who warned you to flee from the wrath to come?
Wrath to come: is the very thing that Jesus saves us from (1Thess 1:10).
8 Bear fruit in keeping with repentance.
Repentance is not only the changing our mind about sin, though it is that as well. It is changing our mind about God and his testimony about his Son as revealed in Scripture. It is believing in the Gospel of Christ for salvation. Repentance and faith are two sides of the same coin. No one repents unless God first pulls that person to himself (John 6:44). Thereupon that person's eyes are opened, he changes his mind about his own sin, and puts his faith in Christ. Belief in Christ is the combination of both repentance and faith. In everyday language the three terms are often used interchangeably, which can be confusing. But we should be clear on how the Bible uses these terms, to avoid confusion in our personal theology. In general, this principle applies to every term used in the Bible. Many misunderstand the Bible because they assume it uses terms in the way that current culture does, and thus they misinterpret God's doctrine. The confusion is exasperated by preachers who themselves misunderstand such Biblical terms. I say this to their shame. Be extremely careful in your own Bible study to understanding words like: mercy, grace, repentance, faith, love, "jealous God" etc. none of which carry the same meaning as their cultural counterparts.
9 And do not presume to say to yourselves, 'We have Abraham as our father,' for I tell you, God is able from these stones to raise up children for Abraham.
10 Even now the axe is laid to the root of the trees. Every tree therefore that does not bear good fruit is cut down and thrown into the fire.
11 "I baptize you with water for repentance, but he who is coming after me is mightier than I, whose sandals I am not worthy to carry. He will baptize you with the Holy Spirit and with fire.
12 His winnowing fork is in his hand, and he will clear his threshing floor and gather his wheat into the barn, but the chaff he will burn with unquenchable fire."
John uses the word fire three times here. The first time fire is used to burn trees that don't bear good fruit (Matt 7:19); the third time to burn useless chaff (Matt 13:40), but the second time it is the fire of baptism with the Holy Spirit. In the negative sense fire denotes the fire of Hell (Matt 5:22, Matt 18:8-9, Matt 25:41, Rev 20:15, Rev 21:8).
Baptism of Jesus
13 Then Jesus came from Galilee to the Jordan to John, to be baptized by him.
14 John would have prevented him, saying, "I need to be baptized by you, and do you come to me?"
15 But Jesus answered him, "Let it be so now, for thus it is fitting for us to fulfill all righteousness." Then he consented.
16 And when Jesus was baptized, immediately he went up from the water, and behold, the heavens were opened to him, and he saw the Spirit of God descending like a dove and coming to rest on him;
17 and behold, a voice from heaven said, "This is my beloved Son, with whom I am well pleased."