Therefore, if anyone is in Christ, he is a new creation; old things have passed away; behold, all things have become new. (2 Cor 5:17)
While Paul’s reference to a new creation summarises the changes which occur within the life of every believer (if anyone), these changes are dramatically focused within his own life.
Love was now the controlling motive (v.14) in the place of hate. Serving the one who died for him had taken the place of selfishness (v.15). True understanding of Jesus, His identity and achievement, have replaced ignorance and error (v.16).
The apostle’s use of vocabulary of the creation narratives of Genesis is striking. it is implied that unbelievers (as Paul had been), are blind (4:4) and live in a darkness analogous to the primal darkness of the first verses of the book of Genesis.
Just as God spoke then, and there was light, so too God now speaks the gospel-word and once again there is light, though it is inward within the heart (4:6). As by the agency of the word of God the world was made, so now, by the word of God, the message of reconciliation, people are remade.
In expressing the great and profound changes that occur in the life of anyone who is in Christ Paul not only affirms that there is a ‘new covenant’ (3:6), there is also a new creation; the old has gone, the new has come (v.17).
— Paul Barnett