At the end of Galatians (6:11-16), Paul picks up on themes from the first part of the letter. In the opening greeting, Paul summarized his gospel as the Son’s self-giving to deliver us from the present evil age. At the end, he says that his participation in the cross means that he is dead to the world. The two declarations say the same thing: To be delivered from the “present evil age” is the same as dying to the “world.”
In 6:13, he claims that those who want the Galatians circumcised are motivated by a desire to boast in the Galatians, and specifically in their flesh, their circumcised flesh. Paul on the contrary boasts only in the cross (v. 14), and the effect of the cross is that he has died to the world and the world has died to him.
The progression from verse 14 to verse 15 is important. Paul says, “the world is crucified to me, and I to the world” and immediately goes on to say that the distinction circumcision/uncircumcision has become meaningless. What matters now is a new creation. The flow of thought indicates that the distinction of circumcision/uncircumcision belongs to the world to which he is now dead. We might paraphrase this way: “being circumcised or not doesn’t matter; what matters is that you participate in a new creation (or have been made a new creation) by the Spirit of God.”
All this has a direct biographical application: When Paul identified with Jesus, the victim of Jewish and Roman judicial murder, the world of which he used to be part died to him. Because he has identified with the Crucified in this way, he was no longer identified by his circumcision or with the circumcised. Yet, he goes on, he does have a mark of his identity in the flesh. Because of his identification with Christ, he has suffered persecution, and he bears the scars, the stigmata, of that opposition, in his body (v. 17).
He’s not like the troublers who want to avoid persecution. He embraces the Crucified, and boasts in the new covenant circumcision that goes with identification with the Crucified. He is identified not with the cut of circumcision but by the cuts and wounds that he suffered for Jesus, a fit return on the wounds Jesus suffered for him.