John Calvin Commentary Colossians 3:10

"and have put on the new man, that is being renewed unto knowledge after the image of him that created him:" — Colossians 3:10 (ASV)

Which is renewed in knowledge. He shows in the first place, that newness of life consists in knowledge—not as though a simple and bare knowledge were sufficient, but he speaks of the illumination of the Holy Spirit, which is living and effective, so as not merely to enlighten the mind by kindling it with the light of truth, but transforming the whole man.

And this is what he immediately adds, that we are renewed after the image of God. Now, the image of God resides in the whole of the soul, since it is not merely the reason that is rectified, but also the will. From this, we also learn, on the one hand, what is the end of our regeneration, that is, that we may be made like God, and that His glory may shine forth in us; and, on the other hand, what is the image of God, of which Moses speaks in Genesis 9:6, the rectitude and integrity of the whole soul, so that man reflects, like a mirror, the wisdom, righteousness, and goodness of God.

He speaks somewhat differently in the Epistle to the Ephesians, but the meaning is the same. See the passage—Ephesians 4:24. Paul, at the same time, teaches that there is nothing more excellent to which the Colossians can aspire, since this is our highest perfection and blessedness: to bear the image of God.