I’m meant to type “ we do it because we believe “
think of how the New Testament begins everyone’s coming to get baptized in water as preparation for the messiah as the Old Testament foretold in its final chapters
“Behold, I will send my messenger, and he shall prepare the way before me:
and the Lord, whom ye seek, shall suddenly come to his temple, even the messenger of the covenant, whom ye delight in: behold, he shall come, saith the LORD of hosts.”
Malachi 3:1 KJV
water
“The beginning of the gospel of Jesus Christ, the Son of God; As it is written in the prophets, Behold, I send my messenger before thy face, Which shall prepare thy way before thee.
John did baptize in the wilderness, and preach the baptism of repentance for the remission of sins. And there went out unto him all the land of Judæa, and they of Jerusalem, and were all baptized of him in the river of Jordan, confessing their sins.”
Mark 1:1-2, 4-5 KJV
then you have the lords word of the new covenant which was foretold in the prophets
spirit
“It is the spirit that quickeneth; the flesh profiteth nothing: the words that I speak unto you, they are spirit, and they are life.”
John 6:63 KJV
and of course the blood of remission which also was foretold in the prophets
“for this is my blood of the new testament, which is shed for many for the remission of sins.”
Matthew 26:28 KJV
See all Of these three agree on the message of gospel that our sins are forgiven , that we have been born again unto God by his provision.
“and said unto them, Thus it is written, and thus it behoved Christ to suffer, and to rise from the dead the third day:
and that repentance and remission of sins should be preached in his name among all nations, beginning at Jerusalem.”
Luke 24:46-47 KJV
The message becomes that we have been given life and the life is in the son of God and his gospel. The three witness of the New Testament promosed from the beginning and manifest in the last times of christs birth , baltism , receiving the spirit , ministering and preach g the word of God , dying for sins , bekng raised up and glorified in the heavens where he sent the spirit to those who believe the witness of the gospel
the water , spirit and blood all
Witness the forgiveness of sins and new birth in righteousness , eternal life