Context: Ephesians — probably a circular letter sent to several churches in Asia Minor (~60–62 AD, during Paul's imprisonment in Rome) — is one of the grandest theological reflections on the Church and God's eternal plan in the NT. The book divides clearly into two halves: theology (chs. 1–3) and ethics (chs. 4–6).

The eternal plan (chs. 1–3): A prolonged hymn to the glory of divine purpose from eternity: election in Christ before the foundation of the world (1:4), adoption as sons, redemption through blood, sealing by the Spirit. Chapter 2 contains the clearest formulation of sovereign grace: "For by grace you have been saved through faith. And this is not your own doing; it is the gift of God, not a result of works, so that no one may boast" (2:8–9). The creation of "one new man" — Jew and Gentile reconciled in Christ — is the mystery that was hidden and is now revealed.

Ethics and spiritual warfare (chs. 4–6): The unity of the Church based on the "seven ones" (4:4–6), the transformed relationships (5–6: husband-wife, parents-children, masters-servants), and the "Armor of God" (6:10–18) — a military image of spiritual warfare using Roman armor as metaphors for Christian virtues.