There are two primary arguments made today to justify baptism. I once made them and practically every denomination does the same. The argument will inevitably start in the Gospel of Matthew with the ministry of John the Baptist. Matthew 3:1-12, "In those days came John the Baptist, preaching in the wilderness of Judaea, (2) And saying, Repent ye: for the kingdom of heaven is at hand. (3) For this is he that was spoken of by the prophet Esaias, saying, The voice of one crying in the wilderness, Prepare ye the way of the Lord, make his paths straight. (4) And the same John had his raiment of camel's hair, and a leathern girdle about his loins; and his meat was locusts and wild honey. (5) Then went out to him Jerusalem, and all Judaea, and all the region round about Jordan, (6) And were baptized of him in Jordan, confessing their sins. (7) But when he saw many of the Pharisees and Sadducees come to his baptism, he said unto them, O generation of vipers, who hath warned you to flee from the wrath to come? (8) Bring forth therefore fruits meet for repentance: (9) And think 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. (10) And now also the axe is laid unto the root of the trees: therefore every tree which bringeth not forth good fruit is hewn down, and cast into the fire. (11) I indeed baptize you with water unto repentance: but he that cometh after me is mightier than I, whose shoes I am not worthy to bear: he shall baptize you with the Holy Ghost, and with fire: (12) Whose fan is in his hand, and he will throughly purge his floor, and gather his wheat into the garner; but he will burn up the chaff with unquenchable fire."
So, who was John baptizing? Jews. His baptism was called the baptism of repentance. However, he also says that Jesus, the one who would come after him and mightier than he, was going to baptize them also, not with water, but with the Holy Ghost and with Fire. That begs the question, "When were they to be baptized with the Holy Ghost?" Well, that happened at Pentecost for those who believed. Well, "When were they to be baptized with fire?" The context makes it clear that the fire baptism that is was not a good thing and it is not the "fire" experience that many charismatics talk about today. Notice the colon at the end of verse 11? They are used before explanations or reasons. Therefore, verse 12 gives the explanation of the reason for this fire baptism. It is obviously about a judgment that was to come after the nation had repented, i.e. Tribulation.
There is a fourth baptism mentioned in Luke 12:49-50 where our Lord said, "I am come to send fire on the earth; and what will I, if it be already kindled? (50) But I have a baptism to be baptized with; and how am I straitened till it be accomplished!" This was a reference to when God the Father baptized his Son with the sins of the world on the cross.