Therefore we have been buried with Him through baptism into death, so that as Christ was raised from the dead through the glory of the Father, so we too might walk in newness of life.Romans 6:4(NASB)
The moment that we were born again, the Holy Spirit takes us from the kingdom of darkness, places us into the kingdom of God's dear Son, and we are baptised into the body of Christ and become one with Him. Sins are forgiven, we are indwelt by the Holy Spirit, fellowship with the Father is reinstated, we become children of God, citizens of heaven, and placed in unity with Christ Jesus our Lord.
Water baptism (though not essential for salvation), is a beautiful outward expression that is carried out in our physical body, which demonstrates the precious, inward, spiritual change when by grace through faith we died to the old self and were raised into newness of life, in Christ.
Paul reminds us that we have been buried with Him through baptism into death, and whether this is singularly seen as figurative (in reference to being baptised into Christ's body at salvation), or literal (through a believer's experience in water baptism), the precious truth remains the same: Just as Christ was raised from the dead through the glory of the Father, so also we might walk in newness of life.
Although water baptism is not a necessary requirement for salvation, it appears that Paul could be using this outward demonstration of immersion to reinforce the splendour and glory of our spiritual baptism into Christ. When we are saved, the old self is dead and buried with Him so that just as Christ was raised from the dead through the glory of the Father, so we too might be given His indwelling life and be empowered to walk in newness of life.
This spiritual baptism means that the new believer has passed from death to life, has been brought into a totally new, yet severed relationship with sin, and placed into a totally new and eternal union with Christ. For by the power of the Spirit and to the glory of God the Father, we are made dead to sin and alive to Christ Jesus our Lord.
Heavenly Father, how I praise and thank You that by grace through faith, I have been made a new creation in Christ and placed in eternal union with my Lord and Saviour. Thank You that my old self has been buried with Christ through baptism into death, severing my slavery to sin. And thank You Father that I have been raised up together with Christ from the dead, made a new creation in Him, and imputed with His righteousness so that I may walk in newness of life. To You be all honour and glory, in Jesus' name, AMEN.