Chapter five reminds the children of God of their duties. Daniel B. Wallace outlines this chapter in the following way:

Overview: The reader will recall that chapter four lays out the ideal for unity within the church and addresses two ways of living: as children of light and as children of darkness. The children of God, of course, are to walk in the light. The writer instructs the children of God that they are to imitate God, as beloved children, and to walk in love following the example of Christ, who sacrificed himself for humankind. This is followed by an "avoid" list of not-to-do activities. The children of God are to walk in the light, and that light is goodness, righteousness, and truth; the light, in fact, mainfests all human activities, revealing them for what they are. Pleasing God requires separation from disobedience and darkness; the children of God are to be wise, to redeem time, to understand the will of God, to be Spirit-filled, and this is evidenced in joy, the speaking of psalms, hymns, spirited songs, melody, and the giving of thanks. The unity of the church that the writer has spoken of in chapter four results when individuals subject themselves to each other. Following this, the writer then talks about the relationship of wives and husbands, children and parents, masters and slaves. What readers must understand is that "right" relationship with other individuals evolves from a "right" relationship with God. This "right" relationship with God and others creates the ideal unity for children of light. Understanding this, one will not misread the subjection of wives to husbands, children to parents, or slaves to masters as intending spineless submission to another who is not himself/herself practicing goodness, righteousness, and truth.

The key then to understanding Ephesians 5 is to understand what it means to be followers of God:

Analysis: The writer of Ephesians opens in the imperative: 

Eph 5:1 Be ye therefore imitators of God, as beloved children;

Eph 5:2 and walk in love, even as Christ also loved you, and gave himself up for us, an offering and a sacrifice to God for an odor of a sweet smell.

If the writer is Paul, he admonishes ethical conduct in which the children of light walk in love after the example of Christ. Christ, he reminds us, gave himself up as an offering and a sacrifice to God. In I. Corinthians, Christ is the Passover, connecting his sacrifice to deliverance from death: 1Co 5:7 "Purge out therefore the old leaven, that ye may be a new lump, as ye are unleavened. For even Christ our passover is sacrificed for us. Hebrews connects this sacrifice to a "once and for all" sacrifice: Heb 10:1 "For the law having a shadow of good things to come, and not the very image of the things, can never with those sacrifices which they offered year by year continually make the comers thereunto perfect.

Not questioned in Ephesians 5.1 is the relationship of God and believers: they are children, and as children, a similitude to the Father must exist. Furthermore, the Christology is developed: Christ's death was an offering to God on behalf of humankind. The sweet odor is clearly a parallel reference to older Jewish practices:

Lev 4:31 And he shall take away all the fat thereof, as the fat is taken away from off the sacrifice of peace offerings; and the priest shall burn it upon the altar for a sweet savour unto the LORD; and the priest shall make an atonement for him, and it shall be forgiven him.

Imitators of God (mimhtai tou qeou). This old word from mimeomai Paul boldly uses. If we are to be like God, we must imitate him.

An offering and a sacrifice to God (prosporan kai qusian twi qewi). Accusative in apposition with eauton  a ransom (lutron) as Christ himself said (Matthew 20:28), Christ's own view of his atoning death. For an odour of a sweet smell (eiß osmhn euwdiaß). Same words in Philippians 4:18 from Leviticus 4:31 (of the expiatory offering). Paul often presents Christ's death as a propitiation (Romans 3:25) as in 1 John 2:2.

Once reminded of right relationship with God and fellow human beings, the  writer now urges from the imitators of God an observance of ethical principles forbidding certain kinds of apparently common practices within the culture:

Eph 5:3 But fornication, and all uncleanness, or covetousness, let it not even be named among you, as becometh saints;

Eph 5:4 nor filthiness, nor foolish talking, or jesting, which are not befitting: but rather giving of thanks.

Eph 5:5 For this ye know of a surety, that no fornicator, nor unclean person, nor covetous man, who is an idolater, hath any inheritance in the kingdom of Christ and God.

Eph 5:6 Let no man deceive you with empty words: for because of these things cometh the wrath of God upon the sons of disobedience.

Eph 5:7 Be not ye therefore partakers with them;

One can simply list clearly wrong behaviors: fornication, uncleanness, covetousness, filthiness, foolish talking, jesting, and empty words.  The reader recalls that Ephesus is the site for the temple of Diana: 

Ephesus
the capital of proconsular Asia, which was the western part of
Asia Minor. It was colonized principally from Athens. In the
time of the Romans it bore the title of "the first and greatest
metropolis of Asia." It was distinguished for the Temple of
Diana (q.v.), who there had her chief shrine; and for its
theatre, which was the largest in the world, capable of
containing 50,000 spectators. It was, like all ancient theatres,
open to the sky. Here were exhibited the fights of wild beasts
and of men with beasts. (Comp. 1 Cor. 4:9; 9:24, 25; 15:32.)

People traveled to Ephesus from many parts of the world, bringing with them offerings for the goddess and participating in the fertility rites. These pagan practices became a temptation for many Jews and new converts to Christianity. The above wrong behaviors clearly have a cause-effect relationship; the effect of being excluded from the kingdom of Christ and God is caused by the behaviors, and the wrath of God comes as a result of disobedience:

Eph 5:5 For this ye know, that no whoremonger, nor unclean person, nor covetous man, who is an idolater, hath any inheritance in the kingdom of Christ and of God.

Eph 5:6 Let no man deceive you with vain words: for because of these things cometh the wrath of God upon the children of disobedience.

Children of God are clearly told:

Eph 5:7 Be not ye therefore partakers with them.

 

The next section of chapter five then outlines two ways: the way of light and the way of darkness:

The children of light are to walk circumspectly in the light provided by Christ. The list continues:

Eph 5:16 Redeeming the time, because the days are evil.

Eph 5:17 Wherefore be ye not unwise, but understanding what the will of the Lord is.

Eph 5:18 And be not drunk with wine, wherein is excess; but be filled with the Spirit;

Eph 5:19 Speaking to yourselves in psalms and hymns and spiritual songs, singing and making melody in your heart to the Lord;

Eph 5:20 Giving thanks always for all things unto God and the Father in the name of our Lord Jesus Christ;

The final verses of Ephesians chapter five address the ideal unity that should evidence itself in the lives of believers:

Eph 5:21 Submitting yourselves one to another in the fear of God.

Eph 5:22 Wives, submit yourselves unto your own husbands, as unto the Lord.

Eph 5:23 For the husband is the head of the wife, even as Christ is the head of the church: and he is the saviour of the body.

Eph 5:24 Therefore as the church is subject unto Christ, so let the wives be to their own husbands in every thing.

Eph 5:25 Husbands, love your wives, even as Christ also loved the church, and gave himself for it;

Eph 5:26 That he might sanctify and cleanse it with the washing of water by the word,

Eph 5:27 That he might present it to himself a glorious church, not having spot, or wrinkle, or any such thing; but that it should be holy and without blemish.

Eph 5:28 So ought men to love their wives as their own bodies. He that loveth his wife loveth himself.

Eph 5:29 For no man ever yet hated his own flesh; but nourisheth and cherisheth it, even as the Lord the church:

Eph 5:30 For we are members of his body, of his flesh, and of his bones.

Eph 5:31 For this cause shall a man leave his father and mother, and shall be joined unto his wife, and they two shall be one flesh.

Eph 5:32 This is a great mystery: but I speak concerning Christ and the church.

Eph 5:33 Nevertheless let every one of you in particular so love his wife even as himself; and the wife see that she reverence her husband.

Far too often, these verses have been used to suggest submission of one sex to another. We are to imitate God, to walk in love as Christ walked in love and gave himself a sacrifice for us. Husbands are admonished to love their wives as they love their own bodies; he that loveth his wife loveth himself. Further, both husband and wife are to submit to one another in the fear of God. Only under this ideal unity is the wife to subordinate herself to the husband, as onto the Lord. Only in this ideal unity is the husband to be the head of the wife as Christ is the head of the church "and gave himself for it." Only under this ideal unity is the wife to be subject to the husband as the church is subject to Christ. Christ gave himself for the church that he might sanctify and clean it, that he might present it to himself gloriously without blemish and holy. If husbands love their wives as they love their own bodies, they will nourish and cherish the wives. Then, the writer tells us the mystery of unity: "we are members of his body, of his flesh, and of his bones." The writer specifically draws out the analogy: "This is a great mystery: but I speak concerning Christ and the church."  This is the mystery of unity revealed in Christ of Ephesians three. Within this mysterious unity, the husband loves his wife even as himself, and the wife sees that she reverences the husband. In chapter six, the writer extends this unity in relationship to children and parents, masters and slaves. Markus K. Barth in the Oxford Companion rightfully points out that the marriage metaphor in Ephesians "must not serve to substantiate male superiority; rather, it promotes the partnership of those married" (189). The writer in Ephesians speaks "of the interrelationship of equally free partners under the unifying lordship of Christ."