That. — So that it might be as the prophet wrote, “He that boasteth, let him boast in the Lord.” This is not a literal quotation, but only an adaptation and paraphrase from the LXX. of Jeremiah 9:23-24. Our only true boasting before God is that we are in Christ, that all we have we owe entirely to Him; we can only glory in, not ourselves or what we have or are, but in the fact that He is our benefactor. Thus, in St. Chrysostom’s quaint words, Paul “always fasteneth them on with nails to the name of Christ.”
This concludes St. Paul’s general explanation of God’s method, and he then turns to his own conduct, to show how entirely it was in harmony with God’s plan, which he has just explained and vindicated.