John’s Baptism is often misinterpreted (in my opinion). Read the following:
1) Malachi 3:1a, “Behold, I will send my messenger (John the Baptist), and he shall prepare the way before me (Christ)…”
2) Read Matthew 3:1-17:
a) See Isaiah 40:3, “The voice of him (John the Baptist) that crieth in the wilderness, Prepare ye the way of the LORD…” Read Matthew 3:3b-5; “And the glory of the LORD shall be revealed…” (Matthew 3:5).
b) Now read Matthew 3:1-12; 13-17.
John’s Baptism was to show “fruits meet for repentance”
See Matthew 3:8, “Bring forth therefore fruits meet for repentance”; for all those awaiting the Coming of the Messiah. See Matthew 3:11, John said, “I indeed baptize you with water… he shall baptize you with the Holy Ghost, and with (in) fire (Judgment at 70 A.D.)”
“And were baptized of him in Jordan, confessing their (those who looked for the Messiah) sins.” (Matthew 3:6)
What sins? Read Luke 1:67-80; especially verses 68-69; “…raised up an horn of salvation for us (the Elect of Israel) in the house of his servant David.” He (Christ) would come through the house of David (verse 69b).
What is the “salvation” spoken of in Luke 1:69? See Luke 1:71-80:
(Luke 1:71) “Saved from our enemies”
(Luke 1:72) “To perform the mercy promised to our fathers… his holy covenant” (see Genesis 17)
(Luke 1:73) That is, “The oath which he sware to our father Abraham” (see Genesis 12:3)
(Luke 1:74-75) “That we being delivered out of the hand of our enemies might serve him (Christ) without fear, In holiness and righteousness…”
Then in Luke 1:76-79, we see the mission of John the Baptist.
The Nation of Israel as a whole had back-slidden into spiritual idolatry, and really, spiritual darkness – from Malachi to John the Baptist was approximately 400 years of no word from God or His prophets. Their sins were disobedience, unbelief, un-holiness, and unrighteousness. They were in spiritual decay.
However, there was a remnant (see Romans 11:5) – such as Elisabeth, Zacharias, Joseph, Mary, Anna, Simeon, etc. – who were awaiting the Coming of the Messiah, the One who would sit on David’s throne, and restore the kingdom to Israel. But, what they did not see was that it (the kingdom) would be spiritual, and not physical.
John the Baptist came on the scene preaching, “And saying, Repent ye: for the kingdom of heaven is at hand” (Matthew 3:2). See Isaiah 40:3, “Prepare ye the way of the LORD, make straight in the desert a highway for our God.”
How was John to do this?
1) By preaching the Kingdom of Heaven was at hand. (Not a physical kingdom, but a Spiritual Kingdom. This Kingdom’s Head would be the Messiah, and its citizens would be Spirit-baptized People, or Regenerated People (Matthew 3:11; 1 Corinthians 12:13).
2) By preaching repentance and proof of repentance through submission to water baptism.
3) By baptizing Jesus
See Matthew 3:13-17; notice in verse 15b, Jesus said, “…for thus it becometh us (John and Christ) to fulfil all righteousness.”
How would this be done – by water immersion, or by the picture depicted in the water baptism of Christ? Of course, it is the latter. It would be by Christ’s Death, Burial, and Resurrection. Christ is the End of the Law; He fulfilled the Law; “For Christ is the end of the law for righteousness to every one that believeth” (Romans 10:4). Paul explains this in Romans 3, 4, 5, and 6, and especially Romans 10:5-21. That is, through the Life and Atonement of Christ, and His Resurrection.
Go back to Luke 1:76-80; here we see John’s mission recorded by Luke:
(Luke 1:76) John would be called “the prophet of the Highest: for thou shalt go before the face of the Lord to prepare his ways”
(Luke 1:77) “To give knowledge of salvation unto his people…”
a) (Luke 1:71) From enemies
b) (Luke 1: 72) “To perform the mercy promised to our fathers…” (To carry out His Promise to Abraham; Genesis 12:3; 17:1-6.)
c) (Luke 1:74-75) To be delivered from the enemies; to serve Christ without fear, in holiness and righteousness before Him. (This happens after Regeneration and Conversion.)
(Luke 1:77b) “…by the remission of their sins.” See Romans 3:24-29; through the Atonement of Christ on the Cross for His Elect
(Luke 1:78) Explains the How; continued from verse 77b:
“Through the tender mercy of our God;”
“Whereby the dayspring (Christ) from on high hath visited us,”
(Luke 1:79) Tells the Why (It is for the Revelation of the future Church, God’s True People, the Children of the Promise (Romans 9:8); Spiritual Israel.)
“To give light to them that sit in darkness”
“And in the shadow of death,”
“To guide our feet into the way of peace.”
John the Baptist’s ministry was:
1) To confirm the Elect of Israel waiting for their Messiah (the future Church; the Spiritual Israel of God) – by baptism (Matthew 3:1-8, 11)
2) To condemn the Pharisees, etc. – by judgement (Matthew 3:7-12)
3) To show by the Baptism of Jesus of How it would be accomplished. That is, through the Life, Death, and Resurrection of Christ; and of His Judgment on Israel (70 A.D).
So, yes, John’s Baptism was used of God to show that He (Christ) would be the Fulfillment of the Law of Moses (Romans 10:4).
But all the above must be understood. For baptism was not taught in the Old Testament as a Law. (Yes, washing for cleansing.) But John’s Baptism was new – for it prepared the way of the Lord Jesus Christ. This is Christ’s First Coming.
Confessing their sins at John’s Baptism was not because of Regeneration – for that did not happen until the Day of Pentecost – but because they were the Remnant of Grace, who would receive the Baptism of the Spirit.