The fifth of Paul's Epistles, and the tenth book in the New Testament, is Ephesians. It was written some time around 61 AD whilst Paul was a prisoner in Rome, awaiting his trial by the Emperor Nero; a persecutor of Christians.
Paul's letter to the Church at Ephesus (in modern day Turkey) is not an admonishment, like some of his other letters, but rather an encouragement. Paul describes the nature of the Church as a living thing; the body of Christ. He then tells the Ephesians to act like Christ's body on earth.
Ephesians 4:1-3
"I therefore, the prisoner of the Lord, beseech you that ye walk worthy of the vocation wherewith ye are called, with all lowliness and meekness, with longsuffering, forbearing one another in love; endeavouring to keep the unity of the Spirit in the bond of peace"