21. Let us listen to that chosen vessel and teacher of the Gentiles, when he had already commended the faith of the people of Rome because of their understanding of the truth. For wishing to teach the unity of nature in the case of the Father and the Son, he speaks thus, But ye are not in the flesh but in the Spirit, if indeed the Spirit of God is in you. But if any have not the Spirit of Christ, he is none of His. But if Christ is in you, the body indeed is dead through sin, but the Spirit is life through righteousness. But if the Spirit of Him Who raised up Christ from the dead dwelleth in you; He Who raised up Christ from the dead shall also quicken your mortal bodies, because of His Spirit Who dwelleth in you Rom. viii. 9–11.. We are all spiritual if the Spirit of God dwells in us. But this Spirit of God is also the Spirit of Christ, and though the Spirit of Christ is in us, yet His Spirit is also in us Who raised Christ from the dead, and He Who raised Christ from the dead shall quicken our mortal bodies also on account of His Spirit that dwelleth in us. We are quickened therefore on account of the Spirit of Christ that dwelleth in us, through Him Who raised Christ from the dead. And since the Spirit of Him Who raised Christ from the dead dwells in us, and yet the Spirit of Christ is in us, nevertheless the Spirit Which is in us cannot but be the Spirit of God. Separate, then, O heretic, the Spirit of Christ from the Spirit of God, and the Spirit of Christ raised from the dead from the Spirit of God Which raises Christ from the dead; when the Spirit of Christ that dwelleth in us is the Spirit of God, and when the Spirit of Christ Who was raised from the dead is yet the Spirit of God Who raises Christ from the dead.