Paul instructs the Thessalonians to 'mark' anyone who refuses to obey his letter, singling them out for corrective social pressure (2 Thessalonians 3:14). The verb implies making a mental or public note, perhaps involving some form of communal awareness or withdrawal of fellowship. It's not formal excommunication but deliberate notice that leads to changed relationship. The goal is redemptive: 'do not regard him as an enemy, but warn him as a brother' (3:15). This measured discipline seeks restoration through community accountability.