9 I wrote to you in my epistle not to keep company with sexually immoral people.
10 Yet I certainly did not mean with the sexually immoral people of this world, or with the covetous, or extortioners, or idolaters, since then you would need to go out of the world.
11 But now I have written to you not to keep company with anyone named a brother, who is sexually immoral, or covetous, or an idolater, or a reviler, or a drunkard, or an extortioner—not even to eat with such a person.
12 For what have I to do with judging those also who are outside? Do you not judge those who are inside?
13 But those who are outside God judges. Therefore “put away from yourselves the evil person.”
I wrote (v.9) — maybe an earlier letter, but likely this one. In Greek, the phrase could mean either. (See v.11.)
world (v.10) — human society
covetous (v.10 and 11) =desiring more (in an evil way)
named a brother (v.11) — one who professes faith
reviler (v.11) — one who uses abusive or violent language
not to eat (v.11) — not to fellowship or socialize
outside (v.12) — unbelievers (Colossians 4:5; 1 Thessalonians 4:12; 1 Timothy 3:7)
judge those who are inside (v.12) — It is proper for an assembly to judge its own members. God will judge those outside (v.13).
evil (v.13) — not just sinful, but having a bad effect. The quote is from Deuteronomy 17:7 and 21:21 — death to sinners in the Old Testament, but only on the testimony of 2 or 3 witnesses