The Book of Ephesians presents a balanced view of the body of Christ and its importance in God's economy. Though Paul writes of his desire for the Ephesians to know about his welfare in prison, this isn't the central purpose of the letter, for within he focuses on several important truths of God's economy, such as unity of the church, right behavior within the home, church and world, and the redemptive work of God in Christ.
Jesus has brought the possibility for unity and love, working in peace among the people of God. Ancient Ephesus existed as a culture fixed on magic and the occult, and thus formed a strikingly appropriate scene for the Book of Ephesians. The situation in Ephesus allowed for Paul to focus emphatically on Christ's victorious ascension as supreme ruler over the church and all other things, now and forever.
Paul's reminders were exhortations, for the Ephesian Christians as their culture enticed them away from living lives of allegiance to the Lord Jesus Christ. Paul emphasized Christ's supreme power as a means of directing their focus. A common Protestant understanding of Paul's letters, including Ephesians, is that Paul desired for everyone who desires Christ-like maturity to receive this important letter.