Paul once again returns to the issue of immorality to ensure that none of it seeps into the community of saints. And the first place where this must be checked is our speech. Our lives are to be holy, and so our talk must be holy.
Speech (3-4): Paul has already addressed our clean break from the old life of immorality and impurity (4:17-19). He now exhorts the church to not let evil vices like these (all considered to be forms of sinful greed) even be named among them. What is proper among saints is to be rid of all such obscenities and foolish talk (“silly talk”). Paul also calls these “coarse jesting” because jocularity is often the form they take. None of these are to have a place among God’s people. Instead, we are to fill our conversations with thanksgiving.
Wrath of God (5-6): The people of God, as those created in His likeness, understand the moral nature of God: He is righteous and holy (4:24). We know with certainty that immoral people have no part in God’s kingdom, and that they instead incur the wrath of God. The true gospel offers forgiveness and salvation to those who repent and believe in the Lord. Promise of salvation without repentance is deception, nothing more than empty words.
 In this context, greed is what fuels immorality and impurity as it did earlier (4:19). Paul applies the verbal form of “greed [ple-o-ne-xi-a (πλεονεξία)]” to immorality elsewhere in 1 Thes. 4:6 as he does here.
 The prohibition here is to avoid speaking of these sins as a form of entertainment. This does not preclude speaking of them to condemn them. Paul himself names these when needed (1 Cor. 6:9-10, 1 Tim. 1:10).
 NASB’s “silly talk [mō-ro-lo-gi-a (μωρολογία)]” is more accurately “foolish talk” (NET, ESV, NKJV). There is a foolishness that is not merely the lack of wisdom but downright sin (Mark 7:22; Psalm 14:1; Prov. 10:23; 13:19; 14:9; 19:3). In this text, “foolish talk” is what disrespects the boundaries set by God for marriage.
 The emphasis here is on speech, which is only a part of God’s will for us (Matt. 5:8; 15:19, 23:25-26).
 The church community should be filled with thanks toward God “for all things” (5:20). Cf. also 1 Thes. 5:18.
 As Paul already addressed earlier (4:17-19), Scripture repeatedly speaks of this (1 Cor. 6:9-10; Gal. 5:19-21).
 This is salvation taught in Scripture (Luke 5:32; 1 Tim. 1:16) and the Ephesians know it first-hand (2:3; 5:8).