Baptism by immersion in water was and is used by Christians showing an outward sign of repentance, which is an inward change of the heart. Water itself does not save, because there is nothing we can do to be saved. Salvation is a total work of God. Christians throughout all ages have used baptism to witness to others their profession as a believer is Jesus Christ. (All bold are my emphases added. Square brackets [ ] indicate meanings of words. King James Version Easy-Reading Bible (KJVER) used.)
Matthew 3:1-3 In those days came John the Baptist, preaching in the wilderness of Judaea, 2 And saying, Repent you: for the kingdom of heaven is at hand. 3 For this is he that was spoken of by the prophet Isaiah, saying, The voice of one crying in the wilderness, Prepare you the way of the Lord, make His paths straight. [See Isaiah 40:3]
What does repent mean? The English word ‘repent’ is derived from the Greek word μετανοέω (metanoeo), which means to think differently or to literally change your mind. In this case, God is telling you to change your mind towards Him. I often tell people, who I am witnessing to, that it is like doing a U-turn in your mind, to follow God’s way.
John the Baptist baptized Jesus before He started His ministry on Earth.
Acts 1:5 For John truly baptized with water; but you shall be baptized with the Holy Ghost not many days hence.
But Christ baptizes with the Holy Ghost.
Mark 1:4 John did baptize in the wilderness, and preach the baptism of repentance for the remission of sins.
Water baptism is a baptism of repentance for the remission of sins. It symbolizes the Spirit washing away your sins, but really it is a profession of your faith that you have repented and now believe.
Mark 16:16 He that believes and is baptized shall be saved; but he that believes not shall be damned.
Believe first then baptism shows salvation. Not as some teach that through baptism one gets saved. That is no what the scriptures teach. In comparing salvation through Christ to the salvation Noah and his family experienced in the Ark the Apostle Peter under inspiration wrote:
1 Peter 3:20,21 Which sometime were disobedient, when once the longsuffering of God waited in the days of Noah, while the ark was a preparing, wherein few, that is, eight souls [persons] were saved by water. 21 The like figure whereto even baptism does also now save us (not the putting away of the filth of the flesh, but the answer of a good conscience toward God,) by the resurrection of Jesus Christ:
Water does not save you, it is when you repent and turn your heart to God. The ‘like figure’ is translated from the Greek word ἀντίτυπον (antitupon), which means an ‘antitype,’ a representative. The ‘type’ is the Ark wherein 8 souls were saved in the flood waters, and the ‘antitype’ is baptism into Christ. Baptism corresponds to or is the antitype of the deluge. The Ark is the symbol for the real thing, salvation through Jesus Christ. Read Noah’s Ark and salvation.
Know this, Jesus said:
John 6:47 Verily, verily, I say to you, He that believes on Me has everlasting life.
Right now! You have everlasting life now. It is not some promise for after you die, but Christ means it begins now.