Baptism by immersion is a representation of something which has already
taken place in the heart of a person the moment he/she surrendered their life to Christ (1 Pet. 3:21). Baptism is the public acknowledgment of our death to self, burial, and resurrection of a new life we have found in Jesus Christ.
As a believer, we have been “crucified” (standing upright in water), we
have been “buried” (immersed into the water), and we have been “resurrected into new life” (raised out of the water). This becomes a picture of a spiritual birth as defined in Rom. 6:3-5 and 1 Corinthians 12:13. It is the outward testimony of the believer’s inward faith. A sinner is saved the moment their faith is placed in the personof Jesus Christ. Baptism then, is a visible and public testimony to that faith.