John of Damascus — on Gal 2:21

“I have been freed through the grace, he says. Therefore, I do not turn back to the Law, nor do I revile the grace as being impotent to vivify. "For if righteousness is through the Law, the Christ has died in vain." Christ died for us, he says, that he might raise us up, justifying us and removing sin from our midst. But if those who attempt to persuade others to be circumcised say that man is justified in the law, then the death of Christ is made redundant.”