If we believe in Christ, Paul says in verse 17, if anyone is in Christ, he is a new creation. The old has passed away; behold, the new has come. This is the process of regeneration. All this is from God, who through Christ reconciled us to Himself and gave us the ministry of reconciliation. He died for us; and our old unbelieving, rebellious self, died in Him. And now our new believing-self lives.