Romans 6:3-4 "...all of us who were baptized into Christ Jesus 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."
Romans 10:13 "Everyone who calls on the name of the Lord will be saved."
Baptizo - "to submerge; to immerse"
The Greek word for "baptism" comes from the cloth dyeing trade. Cloth dipped in dye would be totally colored. The cloth would be totally "identified" with the dye. No part of the cloth not be colored. The term used to describe that procedure is "batism."
When Christians are baptized, they are proclaiming that they are totally identified with the death, burial and resurrection of Jesus. They are saved, surrendered and totally His. That's why Paul called people to remember the meaning of their baptism when the question of Christian conduct was raised.
Water has always been the primary means of physical cleansing. It is natural that it should become used symbolically for spiritual cleansing as well.
Everything in Judaism was washed, making it ceremonially clean. When a Gentile converted to Judaism, they were baptized, that is, they were ceremonially washed. The Jews in Jesus' day easily understood water baptism as a washing or purification.
There are several types of baptism mentioned in the New Testament and they are not to be confused with Believer's Baptism:
John's baptism stood midway between the ceremonial baptism of Gentile converts and Believers' baptism. It was more than ceremonial, but it did not cause anyone to enter the Kingdom of God. It was a baptism of repentance, confession of sin and moral cleansing. It symbolized forgiveness and moral unity; it identified the one baptized with the group awaiting the promised Messiah of whom John preached. It was a baptism that anticipated the baptism of the Holy Spirit and fire that the Messiah would exercise (Matthew 3:11). John's baptism had two focal points:
Jesus' submission to baptism demonstrated His solidarity with sinful men (Matthew 3:13-15). God's answer from heaven, "This is my Son, whom I love, with Him I am well pleased" showed divine approval. It began the movement of salvation and the revealing of His promise of the coming Kingdom.
The baptism of Jesus' followers by His disciples is similar to John's baptism (John 4:1-2 and 3:22-23).
Spirit baptism is the single act of regeneration accomplished by the Holy Spirit when, upon a person's confession of faith in Christ, they are indwelled with His presence and spiritually taken out of the world, sin, and death and placed into the church, the body of Christ (1 Corinthians 12:12-13).