Ambrosiaster — on Gal 2:21 (EPISTLE TO THE GALATIANS 2.21)

“Since a future life is promised to Christians, the one who now lives with God's assistance lives in the faith of the promised life. For this one contemplates his image, having the pledge of the future life, which was procured for us by Christ's love in accordance with God's will. The one who is grateful to Christ is therefore the one who endures in faith toward him. He knows that he has no benefit from anyone but Christ and treats Christ with dishonor if he compares any other to him.”