"What is the symbolism of water baptism?"
Water baptism symbolizes the believer’s total trust in, and total reliance on, the Lord Jesus Christ, as well as a commitment to live obediently to Him. It also symbolizes unity with all the saints (Ephesians 2:19), that is, with every person in every nation on earth who is a member of the body of Christ (Galatians 3:27–28). Water baptism expresses this and more, but it is not an entrance into Christianity. Instead we are baptized because our Lord commanded it and because we obey Him. "Go therefore and make disciples of all the nations, baptizing them in the name of the Father and the Son and the Holy Spirit” (Matthew 28:19).
Before we are baptized, we must come to believe that we are sinners in need of salvation (Romans 3:23). We must also believe that Christ died on the cross to atone for our sins, that He was buried, and that He was resurrected to assure our place in heaven (1 Corinthians 15:1–4). We then turn to Jesus, asking Him to forgive our sins and to be our Lord and Savior, and the moment we do that we are born again, our eternal salvation is guaranteed, and we begin to die to ourselves and live for Christ (1 Peter 1:3–5). At this time we are qualified to be scripturally baptized.
At the river, pool, or baptistery, we let ourselves be completely immersed in the water. This symbolizes burial with our Lord; we are baptized into His death on the cross and are no longer slaves to self or sin (Romans 6:3–7). When we are raised out of the water, we are symbolically resurrected—raised to our new life in Christ to be with Him forever, born into the family of our loving God (Romans 8:16).
The fact that baptism is not a prerequisite for salvation is best seen in the example of a saved man who was not baptized in water, the criminal on the cross (Luke 23:39–43). This self-confessed sinner came to acknowledge Jesus as his Lord while dying on a cross next to Him, and he asked for salvation and was forgiven of his sins. Although he never experienced water baptism, at that moment he was baptized into Christ’s death, and he then was raised to life by the power of Christ’s word (Hebrews 1:3).
Christians have been commanded to be baptized, and we should do so out of obedience to, and love for, our Lord Christ Jesus (John 14:15). Water baptism by immersion is the biblical method of baptism because of its symbolic representation of the death, burial, and resurrection of Christ.