4 There is one body and one Spirit, just as you were called in one hope of your calling;
5 one Lord, one faith, one baptism;
6 one God and Father of all, who is above all, and through all, and in you all.
Paul begs the Ephesians to keep unified (v.3). He now gives the basis for that unity.
body (v.4) — the body of Christ, the Church
Spirit (v.4) — The Holy Spirit
one hope (v.4) — Paul is addressing the one hope of our calling, wherein we find that believers have been called into His grace in Christ. Christ is our hope according to 1 Timothy 1:1: “Paul, an apostle of Jesus Christ by the commandment of God our Savior, and Lord Jesus Christ, which is our hope.” Thus, the hope of salvation (Rapture — deliverance from the wrath to come), the hope of the resurrection, the hope of heaven, and the hope of eternal life are all vested in Him (Galatians 1:4; 1 Thessalonians 5:8; 1 Corinthians 15:19; Colossians 1:5; Titus 1:2). — Sadler, pages 178-179.
Lord (v.5) — Jesus Christ
faith (v.5) — There is some difference of opinion among commentators whether this is referring to the body of Pauline doctrine, the act of believing for the faithfulness of Christ Himself. Since all the items on the list emanate from God to us, I think it probably refers to the body of Pauline doctrine as the one means of obtaining salvation.
baptism (v.5) = lit. “placing into” — not water baptism, but the placing into the Body of Christ by the Holy Spirit