romans 8:9 But ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his. - Free Bible Online

      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!

JFB.