The OT introduced a washing with water to cleanse from ritual uncleanness. In later Judaism, self-baptism was part of the service of conversion. But when John the Baptist appeared preaching his message of repentance, he introduced something totally new: water baptism became a profession of commitment to change. The gospel preaching of early Acts also stresses repentance. Repentance does not mean mere sorrow for sin, but a change of heart and mind.
Those who heard of the resurrected Jesus in Jerusalem were to reverse their opinion of him and to acknowledge him now as the Son of God.
It was appropriate, in view of the meaning of this symbol introduced by John the Baptist, to continue the practice as an open confession of faith: a public testimony to the fact that the individual has changed his or her mind about Jesus and now acknowledges him as the Christ, God’s Savior from sin.
But when John introduced baptism, he also announced that when Jesus came he would “baptize with the Holy Spirit” (Matt. 3:11, Acts 1:5). This promise was kept at Pentecost. From that time on believers have been united to Jesus and one another by the baptizing ministry of the Holy Spirit (1 Cor. 12:13). Thus for the Christian, baptism implies more than repentance. It is a picture of a work which God performs deep within the human personality.
Paul explains the inner reality which water baptism mirrors in Romans 6:1-7. Speaking of the work of the Holy Spirit, Paul teaches that Christians are united with Jesus in his death, so that Jesus’ death is considered ours. Likewise, we are united with Jesus in his resurrection, so that his new life is also ours! The baptism practiced by the early church which was most likely baptism by immersion (cf. Mark 1:10), pictured graphically the burial of one’s old life with Christ and the raising of the believer to new life, to be lived in Jesus’ power.
There is no NT passage that instructs us on the mode of baptism which the church is to practice. Church history shows us that at different times baptism has involved sprinkling, pouring, and immersion. What is important is to realize that, beyond the symbolism of the rite, there lies a great spiritual truth which water baptism is intended to picture. We have died to sin in Christ. We have been raised in him to a new life.
When we accept water baptism we make a public commitment. We will turn our back on all that is evil, to live a holy life that reflects the goodness and the love of our Lord.