The Apostle Paul
Romans 8:9BSB·traditional attribution

You, however, are controlled not by the flesh, but by the Spirit, if the Spirit of God lives in you. And if anyone does not have the Spirit of Christ, he does not belong to Christ.

John Calvin Reformed @genevareformer

9. But ye, etc. He applies hypothetically a general truth to those to whom he was writing; not only that by directing his discourse to them particularly he might more powerfully affect them, but also that they might with certainty gather from the description already given, that they were of the number of those, from whom Christ had taken away the curse of the law.

Matthew Henry Presbyterian @wholebiblehenry

I. The apostle here beings with one signal privilege of true Christians, and describes the character of those to whom it belongs: There is therefore now no condemnation to those that are in Christ Jesus, Rom 8:1. This is his triumph after that melancholy complaint and conflict in the foregoing chapter - sin remaining, disturbing, vexing, but, blessed be God, not ruining.

Commenting on Romans 8:1-9

John Gill Reformed Baptist @doctorgill

But ye are not in the flesh, but in the Spirit,.... That is, ye are not carnal, but spiritual men; or ye are not in a state of unregeneracy, but in a state of grace: the reason proving this is, if so be, or "seeing" that the Spirit of God dwell in you; the inhabitation of the Spirit is a distinguishing character of a regenerate...