Or don’t you know that 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 6:3-4 NIV
In 1 Corinthians 12:13, Paul said that, as believers, we were all baptized by the Holy Spirit into one body, the body of Christ. This immersion into the body unifies us as believers, with each of us gifted to serve the body in some way.
In this passage in Romans, Paul refers to this same baptism. But his focus is different here. Being baptized into Christ means that his experience becomes ours. When we were baptized into Christ, we were baptized into his death on the cross, were placed with him into the tomb, and shared in his resurrection to a new life. The person we were before, who lived in sin and apart from God, is dead and buried. We have been born again (John 3:5-7) into a new life in Christ.
Because of this transformation of my inner man, I am not the person I was before. I may look the same. And, at least initially, I may act much the same. But no longer am I a slave to sin. I have been set free from sin and am now able to serve the Lord instead.
This calls for an active response on my part. Even though I have been baptized into Christ Jesus, the old person I was, does not give up easily. I have to choose to ignore that old man, with his passions and desires. And choose instead to live in a way that honors the one who has given me new life.