God has drawn near to you. He has shown special care for you. He has opened the treasury of His mysteries.
Blessed Jerome writes: "No epistle contains so many mysteries as this one. He speaks of his understanding in order to glorify the grace given to him among the Gentiles, and to urge us to read this epistle with the utmost attention."
He calls the mystery of the calling of the Gentiles here Christ's mystery because its foundation was laid in Christ the Lord. The revelation concerning it was given by the Lord, and it is carried into effect by the Lord Himself.
It is also fitting to call it Christ's mystery because it is essentially connected with the whole work of ordering the salvation of the human race, accomplished by Jesus Christ the Lord.
Its summit is His sitting at the right hand of the Father, in the recapitulation of all things.
Saint Chrysostom says: "You can know how I understood and comprehended either the revelation of God in general, or specifically the truth that He sits at the right hand."
Theophylact continues the same thought: "You can see how much I know the mystery of Christ, that is, that He sits at the right hand of the Father, that He has made us sit there with Him, that in Him both peoples have been built into one new man, and the other things related to this."