Lets start with this verse..
Ephesians 4:5 “One Lord, one faith, one baptism.”
Christ commanded the disciples to baptise…..
Mark 16:15, 16 “And he said unto them, Go ye into all the world, and preach the gospel to every creature. He that believeth and is baptized shall be saved; but he that believeth not shall be damned.”
Matthew 28:19 “Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost:”
Baptism is for those who hear the gospel, believe, and repent.
Acts 2:38 “Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and ye shall receive the gift of the Holy Ghost.”
Matthew 28:19, 20 “Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you alway, even unto the end of the world. Amen.”
Romans 10:9, 10 “That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved. For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation.”
According to these texts one must believe and repent before being baptised. This automatically excludes babies and children, and the bible says nothing of infant baptism.
Now lets see how batism takes place. In baptism, both the candidate and performer go down into the water.
Acts 8:38, 39 “And he commanded the chariot to stand still: and they went down both into the water, both Philip and the eunuch; and he baptized him. And when they were come up out of the water, the Spirit of the Lord caught away Philip, that the eunuch saw him no more: and he went on his way rejoicing.”
Mark 1:9 – 11
“And it came to pass in those days, that Jesus came from Nazareth of Galilee, and was baptized of John in Jordan.
And straightway coming up out of the water, he saw the heavens opened, and the Spirit like a dove descending upon him:
And there came a voice from heaven, saying, Thou art my beloved Son, in whom I am well pleased.”
And finally what does baptism represent for us?
Titus 3:5 “Not by works of righteousness which we have done, but according to his mercy he saved us, by the washing of regeneration, and renewing of the Holy Ghost;”
Colossians 2:12 “Buried with him in baptism, wherein also ye are risen with him through the faith of the operation of God, who hath raised him from the dead.”
Acts 22:16 “And now why tarriest thou? arise, and be baptized, and wash away thy sins, calling on the name of the Lord.”
Romans 6:3, 4 “Know ye not, that so many of us as were baptized into Jesus Christ were baptized into his death? Therefore we are buried with him by baptism into death: that like as Christ was raised up from the dead by the glory of the Father, even so we also should walk in newness of life.”
I think baptism clealy fits in what Christ said it meant to be born again, a spiritual revival, leaving the old behind.