Everything at the end of Ephesians 4 is related to our family identity in Christ. Because we are family, we tell the truth, use our anger correctly, don’t steal from one another, don’t put one another down, and don’t live in bitterness. These actions are borne out of our new identity in Christ. When Paul says to “put on the new self,” it means to remember and live in alignment with this new identity.
The book of Ephesians has a beautiful trajectory to it that starts with a rich theology found in the first three chapters: salvation from God’s point of view in chapter one, salvation from a human point of view in chapter two, and how those both come together in chapter three. Chapter four of Ephesians starts with the word “therefore” and reminds us that chapters 4-6, while practical, are based on the theology of chapters 1-3. We cannot live practically unless we know what we believe; in other words, doctrine shapes what we do.