Romans 8:9-10
9. But ye are not in the flesh, but in the spirit, if so be that the Spirit of God dwell in you—This does not mean, "if the disposition or mind of God dwell in you"; but "if the Holy Ghost dwell in you" (see 1Co 6:11, 19; 3:16, &c.). (It thus appears that to be "in the spirit" means here to be under the dominion of our own renewed mind; because the indwelling of God's Spirit is given as the evidence that we are "in the spirit").
Now—"But." if any man have not the Spirit of Christ—Again, this does not mean "the disposition or mind of Christ," but the Holy Ghost; here called "the Spirit of Christ," just as He is called "the Spirit of life in Christ Jesus" (see on Ro 8:2). It is as "the Spirit of Christ" that the Holy Ghost takes possession of believers, introducing into them all the gracious, dove-like disposition which dwelt in Him (Mt 3:16; Joh 3:34). Now if any man's heart be void, not of such dispositions, but of the blessed Author of them, "the Spirit of Christ." he is none of his—even though intellectually convinced of the truth of Christianity, and in a general sense influence by its spirit. Sharp, solemn statement this!10, 11. And if Christ be in you—by His indwelling Spirit in virtue of which we have one life with him.
the body—"the body indeed." is dead because of—"by reason of" sin; but the spirit is life because—or, "by reason" of righteousness—The word "indeed," which the original requires, is of the nature of a concession—"I grant you that the body is dead . . . and so far redemption is incomplete, but," &c.; that is, "If Christ be in you by His indwelling Spirit, though your 'bodies' have to pass through the stage of 'death' in consequence of the first Adam's 'sin,' your spirit is instinct with new and undying 'life,' brought in by the 'righteousness' of the second Adam" [THOLUCK, MEYER, and ALFORD in part, but only HODGE entirely]. 2 Corinthians 3:15
15. the veil is—rather, "a veil lieth upon their heart" (their understanding, affected by the corrupt will, Joh 8:43; 1Co 2:14). The Tallith was worn in the synagogue by every worshipper, and to this veil hanging over the breast there may be an indirect allusion here (see on 1Co 11:4): the apostle making it symbolize the spiritual veil on their heart.