If the meaning of baptism could be summarized in one word, that would be identification. Baptism speaks primarily of personal, public identification with Jesus Christ.
In Romans 6:3-4, the Apostle Paul puts the matter this way:
“Don't you know that all of us who were baptized into Christ were baptized into his death? We were therefore buried with him through baptism into death in order that, just as Christ was raised from the dead through the glory of the Father, we too may live a new life.”
Notice the strength of the expressions "baptized into Christ," "baptized into His death," and "buried with Him in baptism." Someone may suggest that the primary reference here is to Spirit baptism. That's true, but at the very least, water baptism is in the background of this passage.
Baptism in the Bible:
Baptism requires water. (Matthew 3:11)
"I indeed baptize you with water unto repentance, but He who is coming after me is mightier than I, whose sandals I am not worthy to carry. He will baptize you with the Holy Spirit and fire."
Baptism required plenty of water. (John 3:23)
"John also was baptizing at Aenon near Salim, because water was plentiful there, and people were coming and being baptized"
Baptism requires going down into the water. (Acts 8:38-39)
"And he commanded the chariot to stop, and they both went down into the water, Philip and the eunuch, and he baptized him. And when they came up out of the water, the Spirit of the Lord carried Philip away, and the eunuch saw him no more, and went on his way rejoicing."
Baptism requires coming up out of the water. (Matthew 3:16, Acts 8:39)
Furthermore, the figures of speech used by the Apostle Paul accord well with immersion. Baptism is called a “burial” in Romans 6:4 and Colossians 2:12. Baptism is “into his death” and involves being “raised to walk in newness of life.”
It is difficult to see how sprinkling or pouring could convey these meanings.
Finally, the testimony of church history is that immersion was indeed the mode of baptism practiced in the early church.
How Baptism Relates to Jesus
It means we have turned from the old life of sin to a new life in Jesus Christ.
It means we are publicly identifying with Christ's death, burial, and resurrection.
It means we are openly joining the ranks of those who believe in Christ.
When you are baptized, you are visually preaching the gospel. As you stand in the water waiting to be baptized, first, you symbolize Jesus dying on the cross. Second, you symbolize Jesus buried in the tomb as you are lowered into the water. As you are raised from the water, you symbolize Jesus rising from the dead.
And since you personally are being baptized, you are also saying, "I died with Jesus Christ, I was buried with Him and now I am raised with Christ to a brand-new life."
In short, in your baptism, you are confessing the faith without using any words at all. And your confession in your baptism will be more effective with your friends than any sermon the pastor preaches on Sunday morning—more effective because it comes directly from you.
The Greek word translated as “baptize” is the verb baptizo. Most contemporary lexicons say the primary meaning is “to dip, plunge, immerse.” The secondary meaning is to “bring under the influence.” Dr. Merrill Tenney notes that “after making allowances for certain occasional exceptions, such as passages where washing is implied, the etymological meaning indicates that baptism was originally by immersion." (Basic Christian Doctrine, p. 257)
How important is your baptism?
It is your personal identification with the greatest act of human history—the death, burial, and resurrection of Jesus Christ. Baptism doesn't save you—salvation comes by faith alone (Ephesians 2:8-9). Your guilt before God is removed the moment you trust in Christ. But baptism is your personal testimony to, and the inward assurance of, your passage from the old life to the new life.
"Baptism, which corresponds to this, now saves you, not as a removal of dirt from the body but as an appeal to God for a good conscience, through the resurrection of Jesus Christ" (1 Peter 3:21)
"For as many of you as were baptized into Christ have put on Christ." (Galatians 3:27)
When we enter the waters of baptism, we proclaim the gospel message. Jesus died for our sins, was buried, and lives again. By joining in baptism, we’re identifying ourselves with Him. Romans 6:4 says we have been buried with Him through baptism into death. We’re now dead to the power of sin. Being raised up out of the water expresses our new life in Christ and our union with Him.