The Greek noun ethos (ἔθος) means custom, habit, or tradition — a practice established by repeated use. It appears in Luke 1:9, 2:42, 22:39; John 19:40; Acts 6:14, 15:1, 16:21, 21:21, 25:16, 26:3; 28:17; and Hebrews 10:25 in various contexts of Jewish, Roman, and Christian practice.
The word ethos appears across both positive and negative contexts in the New Testament. Jesus went to the Mount of Olives 'as his custom was [ethos]' (Luke 22:39) — His prayerful habit at a place of intimacy with the Father. Hebrews 10:25 uses it to warn against the bad habit of 'giving up meeting together, as some are in the habit of doing.' The Epistle of James notes that Abraham's faith was 'worked together with his actions.' Our ethos — the sum of our habits and customs — shapes our character and reveals our true values. This is why Hebrews commands: cultivate the habit of assembling, of encouraging one another, all the more as the Day approaches. Good habits are the architecture of a holy life.