Bede — on 1Pet 3:18 (Commentary on the Catholic Epistles)

“That He might present us to God, indeed mortified in the flesh, etc. Concerning this mortification of the flesh and vivification of the spirit, which those who labor for the Lord through patience possess, the apostle Paul also speaks: Though our outer self is wasting away, our inner self is being renewed day by day (II Cor. IV). Therefore Christ offers us to God the Father when we joyfully sacrifice ourselves for Him through the mortification of the flesh, that is, He presents our praiseworthy life in the sight of the Father. Or certainly, He offers us to God when He introduces us, freed from the flesh, into the eternal kingdom. Indeed, as it is said: Made alive by the Spirit: Saint Athanasius, bishop of Alexandria, does not refer this to the human spirit, which is better vivified when the flesh is mortified, as the prophet says about the Lord: To revive the spirit of the humble, and to revive the heart of the contrite (Isaiah LVII), but rather refers it to the grace of the Holy Spirit, who gives eternal life to those mortifying their flesh. For he also uses this testimony against the Arians, who contradict the equality of the Holy Trinity, affirming that by the indivisible unity of divine operation, the Father gives life, the Son gives life, and the Holy Spirit gives life. The Father and the Son, as it is written: For as the Father raises the dead and gives them life, so also the Son gives life to whom He will. The Holy Spirit, indeed, as it is declared by this testimony, which is said of the Son, that He might present us to God, indeed mortified in the flesh, but made alive by the Spirit; and therefore, where the operation is one, the substance or essence cannot be different.”