B. Devoted to Doing Good (3:8) and Warned to Avoid the Unprofitable (3:9-11)

This is the fourth occurrence of doing good, the earlier ones being in 2:7, 14, and 3:1, with one further occurrence in 3:8. Sound doctrine promotes a lifestyle that is excellent (Gk., “good”) and profitable for all.

This sharply contrasts with the behavior described in 3:9, which is unprofitable and useless and which the believer is to avoid. The references to genealogies and quarrels about the law in 3:9 may reflect the influence of Jewish legalism (see 1:10, 14; 1Ti 4:1-7; 6:3-5).

Vv.10-11 lay out guidelines for dealing with a divisive person, one who creates factions. Warning/refuting according to sound doctrine is a responsibility of the church leader. A divisive person is warped (Gk., “turned inside out”) and sinful. Warped is past tense while sinful is present tense. Past attitudes determine present actions. Divisive people have made their own judgment: They stand self-condemned.