5:16 Walk in the Spirit. The Christian “walk” is synonymous with the daily Christian way of living (compare John 8:12; Colossians 2:6). We have been indwelt by the Holy Spirit and are new creations in Christ, so we do not need the threatened penalties of the law to constrain us to refrain from sin. “The love of Christ constraineth us” (II Corinthians 5:14), and a conscious commitment to the leading of the indwelling Spirit by God’s Word will enable us to live in a way pleasing to Him who has saved us, not to yield to fleshly lusts.
5:16 the lust of the flesh. This phrase, “lust of the flesh,” is also used in Ephesians 2:3, II Peter 2:18, and I John 2:16. The conflict between the Spirit and the flesh is prominent throughout Scripture, first mentioned as such in Genesis 6:3.
5:19 these. The apostle here lists seventeen typical sins of the “flesh.” The list is typical, not exhaustive, as he adds the phrase “and such like” to cover the rest. These include sexual sins, religious sins, moral sins, violent sins, mental sins—everything which violates the laws of God and man. It seems anomalous that teaching that salvation depends on obedience to the works of the law would actually lead to law-breaking, but it often does just that. Our sinful human nature somehow makes that which is prohibited more desirable.
5:20 variance. “Variance” means “intense dissensions;” “emulations” means “bitter jealousies;” “seditions” means “factious divisions.”
5:21 do such things. Those who “do” such things—that is, “habitually do” such things—thereby indicate they are not really led by the Spirit, and therefore not really saved.