Summary:
Paul told the Thessalonians to disfellowship the men who were walking disorderly by not working (v.14) out of love, so he reminded them not to count them as enemies (v.15). This is similar to what Moses taught (Lev.19:17) in the context of loving your brethren (v.18). This is also similar to how, if you love your son, you will chasten him and not allow him to continue in rebellion against your authority. If you love your brother, you don’t let him continue in rebellion against God, you chasten him by having no company with him. Hey, if you are supposed to love your brother enough to return his animal when it goes astray, (Deut.22:1), shouldn’t you act if his soul goes astray?
In saying “count him not as an enemy” (IITh.3:15), Paul may have been thinking of the fornicator that the Corinthians disfellowshipped (ICor.5:9-13). To their credit they did, but then wouldn’t let him back into the assembly (IICor.2:6-8). Causing “overmuch sorrow” is not how you love a brother! So Paul told them to “confirm” their love for him (v.8). Just because a brother falls into sin, or quits going to work, is no reason to ostracize him forever. By the way, if you are the one being disobedient and find yourself disfellowshipped, react as the psalmist did (Ps.141:5).
As we said, first the Corinthians wouldn’t put the man out of the assembly, then they wouldn’t let him back in. These extremes are the “devices” of Satan that Paul warned about in that passage (IICor.2:11). Some men refuse to be the head of the home God says they are, some take it too far. Some parents refuse to spank their kids, some break their bones. Some Christians are too carnal like the Corinthians, others are too legalistic like the Galatians. Some Christians don’t rightly divide the Word and think everything is written to them, our Acts 28 brethren divide it too much and are left with only Paul’s prison epistles.
When Paul prayed that “the Lord of peace give you peace by any means” (IITh.3:16), the Lord of peace is Christ, who went to great means to give you peace with God. God could “by no means” clear guilty sinners (Ex.34:6,7), and not even the rich could “by any means” redeem his brother (Ps.49:6,7). And if you wind up in “hell” (Mt.5:22) you will “by no means” come out (v.26). But while there was no means by which God could clear sinners under the Old Covenant of the Law, Christ “by means of death” can clear believers under the New Covenant of grace (Heb.9:15).
But if the Thessalonians had “peace with God” (Rom.5:1), why does Paul pray the Lord will give them peace? Well, not all who have peace with God feel like they have it, so Paul prays they will have it experientially. It’s like how God says Israel will “possess their possessions” in the kingdom (Obadiah 17). God told them they’d possess the land (Gen.17:8), but they never fully did. He told them they’d possess the nations (Deut.9:1) but they never fully did. But in the kingdom they will. In our kingdom in heaven we will fully possess the peace God says is ours, but Paul is praying we will possess it now. All Israel had to do was believe God when He said those things were theirs, and all we have to do is believe God when He says peace is ours.
Once you possess your possessions you have to hold them or lose them. You wouldn’t think anyone could corrupt the simplicity of “Christ died for our sins…and…rose again” (ICor.15:3,4cf.IICor.11:3) but they did when the Corinthians stopped believing in the resurrection and lost their peace. But the “peace” Paul prayed the Thessalonians would retain was that of the pretrib rapture. In his first epistle to them Paul says he was concerned “lest by any means” the devil had dispossessed them of their possession of that blessed hope, and Paul lists the means he used (IITh.2:1,2).
Why’s Paul add “the Lord be with you” (IITh.3:16)? Well, when Saul said that to David, he meant the Lord who was with him when he killed the bear and lion would be with him against Goliath. In the same way, Paul is praying the Lord who defeated Satan at Calvary will continue to be with us. He will be, of course; Paul is praying according to the revealed will of God, just as he was in the “salutation” (IITh.3:17) in Verse 18. The grace that saved us will always be with us, but there is nothing wrong with saying “grace be with you”!