Scripture answers itself. So let's take a look here. "MUST" means salvation depends on it. We must be born of water and the Spirit. So what we must do is consider all the kinds of water that the Scriptures mention, since scriptures back up other scriptures in harmony. OK, so let's list waters...
Water from the sea
Water from amniotic fluid
Water of Life (Jesus)
Living Water (Jesus/Word of God
Waters (multitudes of people)
Sky
(If you know any other relevant waters, please mention it)
OK so now we must take out of the list any not mentioned in scripture. That would be amniotic fluid. It makes no sense anyways. Only modern day language calls it water- but it is not water any more than blood, or any other bodily fluid.
Moving on, we are not physically nor spiritually born from the sky or from multitudes of people (only a mother and father), so those come off the list as well. So what we have left is Jesus, the Word (same), and physical water...
We were already born physically, so to be born again of both water and the Spirit means to be spiritually born of both water and the Spirit. There is no question that Jesus is Living Water that we cannot spiritually live without. Jesus told the woman at the well, "This water will make you thirst again, but I can give Living Water." He was speaking of Himself. So how do we get this Living Water? ...
Well Jesus is that water, so we must be in Him to have that water of life. How do we then get into Christ, since those in Christ will be saved? The bible mentions only one thing that puts us in Christ- we are baptized into Christ. (Romans 6:3). How? Jesus showed us how. He did not get baptized to wash away His sins, He had none. He did it because we must follow His lead. Remember, when a command of God uses the word 'must' our salvation depends on it.
How did Jesus get baptized? Did He say a sinners prayer? No. Did He simply have faith that God exists? No. Was He sprinkled with water? No. Scriptures say He came up out of the water. That does not happen with sprinkling. What happened next? The Holy Spirit came. And what did Peter say? "Repent and be baptised all of you, and you will receive the Holy Spirit." Do not get tripped up on receiving the Holy Spirit before or after baptism. Having the Holy Spirit is not salvation, having Christ's blood is salvation. Peter says we will receive it, he doesn't say when.
Did speaking face to face with Jesus save Paul? No, because Jesus told him to go into the city where he will be told what he must do. Was Paul told to fast or pray? No, that is not what saved him. Fasting, praying, being prayed for, being healed, having faith- none of these things saved Paul, so what did? What was he told he must do? Ananias said "What are you waiting for, arise, be baptised and wash away your sins, calling on the name of the Lord."
Philippe and the Ethiopian Eunuch stopped where there was much water, so that he can be baptised. Why did Philip disappear after? Because that was it, what needed to be accomplished. It was not faith, not studying, that saved the Eunuch. He was born again by water. Which water? There is nothing magical about physical water that saves our souls. However, we are in physical bodies- therefore in order to obey God spiritually it sometimes requires what we do physically.
Please understand, water baptism saves us, but only because it is when we come in contact with Living Water (baptised into Christ). During baptism God performs circumcision of the heart with Christ's blood. The ark saved Noah, but not before building it and stepping into it. If he did not build it or go into it he would not be saved by it. In the same way, being dunked under water does not save us itself, but obeying God to do so puts us in Christ where we are saved.
The bible says that the gospel is the death, burial, and resurrection of Jesus Christ. It also says that we must obey the gospel. "With flames of fire (hell) He will take vengeance on those who know not God and who obey not the gospel of His Son." (Whoever does not call that salvation-dependant, wow, just wow). So what does this mean? Only martyrs for Christ will be saved? Must we die on a cross as He did? The answer to this is in Romans 6. It says 'like this', and to what does that refer? Baptism. If we join Him in His death like this (baptized into Christ's death), then we will join Him in His resurrection.
Baptism is a death, burial, and resurrection. After being water baptized, Jesus said He had a baptism to undergo, and how greatly distressed He was until it was accomplished. Who gets that stressed about water baptism? No, He was speaking of His death. When we get baptised (born again) we die to ourself, bury our sinful self in the watery grave, and are raised to newness of life.
