The Apostle Paul
Romans 8:14ASV·traditional attribution

For as many as are led by the Spirit of God, these are sons of God.

Geneva Bible Notes Reformed

For as many as are led by the Spirit of God, they are the sons of God. (16) A confirmation of this reason: for they are the children of God who are governed by his Spirit, therefore they will have everlasting life.

John Calvin Reformed

14. For whosoever are led by the Spirit of God, etc. This is a confirmation of what has immediately preceded; for he teaches us, that those only are deemed the sons of God who are ruled by his Spirit; for by this mark God acknowledges them as his own people.

Jamieson-Fausset-Brown Reformed

For as many as are led by the Spirit of God, they are the sons of God, they, &c.--"these are sons of God." Hitherto the apostle has spoken of the Spirit simply as a power through which believers mortify sin: now he speaks of Him as a gracious, loving Guide, whose "leading"--enjoyed by all in whom is the Spirit of God's dear Son--shows that they also are "sons of God."