Albert Barnes Commentary Romans 8:5

"For they that are after the flesh mind the things of the flesh; but they that are after the Spirit the things of the Spirit." — Romans 8:5 (ASV)

For they that are after the flesh. Those who are under the influence of the corrupt and sinful desires of the flesh (Galatians 5:19–21). Those who are unrenewed.

Do mind the things of the flesh. They are supremely devoted to the gratification of their corrupt desires.

But they that are after the Spirit. Those who are under its influence; who are led by the Spirit.

The things of the Spirit. Those things which the Spirit produces, or which he effects in the mind (Galatians 5:22–23).

This verse serves as an illustration and is designed to show that the tendency of religion is to produce a devotion to God's service as complete as people previously rendered to sin; that is, they would be fully engaged in that to which they had devoted themselves. Therefore, since the Christian had devoted himself to the service of the Spirit, and had been brought under his influence, it was to be expected that he would make it his great and only object to cherish and cultivate the graces which that Spirit would produce.