The will of the Lord is that we live carefully, cautiously, always matching our lifestyle with the teachings of Scripture.

(5:17) “Unwise” is aphrōn (ἀφρων), “without reason, senseless, foolish, stupid, without reflection or intelligence, acting rashly.” “Understanding” is suniēmi (συνιημι), “to set or bring together, to put the perception with the thing perceived, to set or join together in the mind,” thus, “to understand.” The word speaks of reflective thinking. The verb is present imperative in a prohibition, forbidding the continuance of an action already going on. Ginomai (Γινομαι) is the verb, meaning “to become.”

To be wise is to know the will of the Lord (5:17). Here Lord is not restricted to Christ (contra Best, 1998:506; Lincoln: 343), even if it includes Christ. The phrase has both a large and a specific meaning. On one hand, it refers to knowing the height, depth, width, and length of the mystery of the will of God as revealed in Christ, which is to gather up all things in Christ (cf. 1:9–10; cf. 3:18–21). This entails an appreciation for God’s gracious intentions for the disobedient (2:1–10), specifically for Gentiles (2:11–22; chap. 3). It also means understanding what kind of behavior God expects from the community that constitutes God’s home. It means imitating God and Christ (4:32–5:2). It means learning Christ and the truth in Jesus (4:20–21). All this can be summarized as discerning what gives God pleasure (cf. 5:10).

5:17 foolish Refers to being ignorant of God’s values, concerns, and authority (compare Pss 14:1; 53:1).

will of the Lord God’s will is to bring all of creation under the authority of Christ (Eph 1:9–10).

“So do not be foolish, but understand what the will of the Lord is. Do not get drunk with wine, for that is debauchery …” (5:17–18a). Use good judgment. This line is almost limitless in application. Use good judgment in choosing your friends, a spouse, the place you work, raising your children, the ways you order a church, the ways you spend your money, and the list goes on.

I know I’m supposed to use good judgment, but sometimes I don’t. Paul connects “Do not be foolish” to “Understand what the will of the Lord is.” If we can stay in touch with “the will of the Lord,” we will be kept from foolishness.

For church people there is an especially perplexing issue here. I’ve heard people argue before a committee or in a church business meeting that they were in touch with “the will of God.” God had told them God’s intentions, and they were simply passing along this insight to the group. But some of the stuff argued by those people sounded like foolishness to me. But, if I were to speak against them, I would likewise be speaking against “the will of God.” However, if somebody does not speak up, the group is likely to do foolishness. What do you do? Many people have pressed their point by declaring they were “speaking for God.” God’s will and good sense usually travel together.

Paul used an illustration of acting foolishly: “Do not get drunk with wine, for that is debauchery …” (5:18a). Seventy-five years ago, every Methodist, Baptist, and Presbyterian church was teaching the evils of alcohol. Many churches had a “temperance lesson” every quarter. That has passed. But “the problem” is still around. Yet we are silent. I wonder why.

The will of God is often tied to mystery and vision. But more often it is synonymous with using good judgment. Paul said as much when he wrote, “Do not be foolish, but understand what the will of the Lord is” (5:17). When the will of God stamps out foolishness, churches spend their money on the right things. People make good choices about the next preacher. The best examples wind up teaching children and youth in Sunday school. The deacons choose the right chair. Churches don’t get too deep into debt, and when they do, they don’t stay in debt very long. And on and on this list could run. No foolishness. Use good judgment.

God has given us a mind (v. 17a). “Understanding” suggests using our minds to discover and do the will of God. Too many Christians have the idea that discovering God’s will is a mystical experience that rules out clear thinking. But this idea is wrong—and dangerous. We discover the will of God as He transforms the mind (Rom. 12:1–2); and this transformation is the result of the Word of God, prayer, meditation, and worship. If God gave you a mind, then He expects you to use it. This means that learning His will involves gathering facts, examining them, weighing them, and praying for His wisdom (James 1:5). God does not want us simply to know His will; He wants us to understand His will.

Ver. 17. Wherefore be ye not unwise, &c.] No one would be thought to be unwise, but such are, who do not redeem time, and are ignorant of the will of the Lord; believers should not act the unwise part, neither in their talk, nor in their walk and conversation, nor in their use of time: but understanding what the will of the Lord is; or of God, as read the Alexandrian copy, the Vulgate Latin, Syriac, and Ethiopic versions: there is the secret will of God, which is the rule of all his proceedings; and is unknown to men, till facts make it appear; this is always fulfilled, and sometimes by persons who have no regard to his revealed will; to this the wills of the people of God should be always resigned: and there is his revealed will, which lies partly in the Gospel; which declares it to be his will, that Christ should work out the salvation of his people, which is what he came to do; that whoever believes in him shall be saved; that all that are redeemed shall be sanctified; and that they shall persevere to the end, and be glorified; and partly in the law, in the precepts and commands of it, which contain the good, perfect, and acceptable, will of God: and the understanding of it is not a mere speculative knowledge of it, but a practical one; when a man not only knows, but does the will of God, and his heart and actions agree with it; and this is to be done in faith, in virtue of grace and strength received, with a view to the glory of God, having no dependence on what is done; and to the right understanding of it, so as to act according to it, as should be, the word of God, and the illuminations, instructions, and grace of the spirit, are necessary: the Alexandrian copy, Syriac, Arabic, and Ethiopic versions, read the words as an exhortation, understand ye the will of God.

understanding—not merely knowing as a fact (Luke 12:47), but knowing with thoughtful understanding. the will of the Lord—how each opportunity is to be used. The Lord’s will ultimately is our “sanctification” (1 Thess. 4:3); and that “in every thing,” meantime, we should “give thanks” (1 Thess. 5:18: cf. above, v. 10).

2. Understanding the Will of God (vs. 17). The primary consideration for the Christian must never be what is most profitable financially, what is most pleasurable or enjoyable, or what will bring the greatest personal advantage or honor. His first concern is to discern what God wills him to be and to do. This course is the way of wisdom, and anything short of it betrays a mind lacking in moral intelligence.

This understanding of the will of the Lord is the practical understanding demonstrated in actually applying God’s revealed will (His “law”) to life. One cannot help remembering the oft-stated view of the O.T., that “The fear of the Lord is the beginning of wisdom.” And this “fear” is manifested in bringing one’s life into submission to God’s law.

5:17 Understand what the Lord’s will is summarizes the two philosophies of life described in vv. 1–17. The world’s lifestyle is characterized by moral and spiritual darkness. The philosophy for godly living is characterized by moral and spiritual light, and its goal is to imitate God and his love