Ephesians 3:1-13 is actually a digression in the book. Paul proceeds to write about how 2 seemingly irreconcilable peoples - Jews & Gentiles - are formed into a unity called 'the Church".
How does this relate to us today? Is the church really that important? What follows is truly mindboggling.
Ephesians 5:1-14 begins with a call to imitate God - the most difficult task God will ever ask of us. Do Christians want to grow in holiness for Jesus, or is just self improvement so that they are respectable to others? The desire to be a "better person" can possibly be a selfish pursuit, if motives are wrong. Is it important that we look good as Christians or that Jesus gets the glory by our practical love for Him - in terms of obedience?
(See also Steve White's sermons on Ephesians in the same series.)