“…that no one should take advantage of and defraud his brother in this matter, because the Lord is the avenger of all such, as we also forewarned you and testified“
because the Lord is the avenger of all such,
An “avenger” is one who exacts a penalty from a person. The Lord will personally punish sexual sins. God always maintains this right.
The word “all such” refers to any sin: adultery, fornication, homosexuality, or sex with animals. Those who commit such sins still have God to reckon with. God keeps books on this issue, and He is an excellent accountant!
“Beloved, do not avenge yourselves, but rather give place to wrath; for it is written, ‘Vengeance is Mine, I will repay,’ says the Lord” (Romans 12:19).
We do not have to get even for immorality perpetrated against us. God will do that for us. There is no need for recrimination because God executes vengeance for us. Commit it to the Lord. The Lord will also mend your broken spirit. He will deal with shame, sorrow, and disgrace.
as we also forewarned you
The word “forewarned” is literally to say before. This is the idea of warning someone of some future serious consequence.
“…envy, murders, drunkenness, revelries, and the like; of which I tell you beforehand, just as I also told you in time past, that those who practice such things will not inherit the kingdom of God” (Galatians 5:21).
The word “testified” is a strong word for giving testimony. Literally, this word comes from two Greek words: through and testify – to testify through. Paul thoroughly warned the Thessalonians of God’s judgment of sexual sin. Paul bore solemn witness about what God would do with those who “take advantage” and “defraud.” The solemn warning here may be due to the close tie between religion and sex in Thessalonica.
God will deal with sexual wrongs against us.
Sexual sin steals from others. It steals both from the person and from their mate. These sins have negative social impact. Sexual sin violates Christian brotherhood.
“You shall not covet your neighbor’s house; you shall not covet your neighbor’s wife, nor his male servant, nor his female servant, nor his ox, nor his donkey, nor anything that is your neighbor’s” (Exodus 20:17).
Not only do these sins damage families but the people who commit these sins. Children suffer, parents suffer, and the self suffers. This is why God “avenges” these sins. No one escapes the pain of these choices. There are predictable costs to these sins. People give the excuse, “Well, I just fell in love. I couldn’t help myself.” Ministers who run off with someone hurt their congregations. Those congregations suffer for years to come.
“Marriage is honorable among all, and the bed undefiled; but fornicators and adulterers God will judge” (Hebrews 13:4).
God will forgive sexual sins, but He will also deal with these sins just as He did with David’s sin with Bathsheba. David’s scars lasted until he died.