Verses 1-20
More about the new standards (5:1-20)
Just as children follow the example of their parents, so Christians must follow the example of their heavenly Father. Their love, then, will not be mere words, but will show itself by self-sacrifice, just as Christ's love did (5:1-2).
Converted pagans had a special problem in that many of the sinful practices they once engaged in were still widespread in the society in which they lived. One way to overcome the temptation to such practices was not even to speak about them. They should certainly not joke lightheartedly about them, because people who practise such things are enemies of God's kingdom (3-5).
Besides being careful about what they say, Christians should be careful about what they hear. They must examine what people say, whether concerning religion, morals or anything else, to see whether such people are on the side of Satan (darkness) or Christ (light). Only by careful testing will Christians know whether a thing is pleasing to God or not, whether it belongs to the light or to the darkness (6-10). If the lives of Christians are pure, they will show up the sins of others, just as light shows up dirt. Any who stir themselves from their moral laziness can be cleansed, if they allow themselves to be examined in the light of Christ (11-14).
Christians must be alert at all times. They must act wisely and display the worth of Christianity to a sinful world (15-17). In former days they might have tried to overcome depression or find enjoyment by drinking till they became drunk. Now that they are Christians, they should open their lives to God and allow God's Spirit to control them. They will find true joy in having fellowship with other Christians, singing praises together and giving thanks to God (18-20).
Verse 21
Christian relationships (5:21-6:9)
People can have good relations with one another only as they consider one another. When they insist on their rights without considering others, they only destroy harmony and fellowship (21).
In the next section Paul illustrates this principle in certain family and social relationships. In 5:22-33 he considers the the case of husbands and wives, in 6:1-4 the case of parents and children, and in 6:5-9 the case of masters and servants. In union with Christ, people within these various categories share the same spiritual status (Galatians 3:28). But in the family and in society, people have different functions, and they must know how they should act towards each other.
If a family is to enjoy genuine contentment, it must have leadership, and this responsibility rests with the husband. As the church submits to Christ, so the wife is to submit to her husband (22-24). Christ's headship of the church, however, was shown not through the use of force, but through the sacrifice of himself for her, so that she might be pure and faultless (25-27). Likewise the husband's headship of the wife is shown not by forcing his authority upon her, but by treating her as equal with himself (28-29). There is unity between husband and wife, as there is between Christ and his church. This unity is the basis of the relationship (30-33).
Paul refers to the Ten Commandments to support his teaching that in the Christian family, children have a responsibility to obey and respect their parents. Although this is a duty, it will also bring a reward (6:1-3). Parents, on their part, must combine wise teaching with understanding discipline if they are to expect the children's respect and obedience (4).
Slavery was so widespread in the world of the first century that the social, political and economic order of the day could scarcely survive without it. Paul knew that he could not expect slavery to be abolished immediately, but he worked towards its abolition by encouraging new attitudes. In most churches there were Christian slaves and Christian masters, but their attitudes to each other had to change now that they were both 'in Christ'. The same principles can be applied to employers and employees in any society. Christians must work honestly and well for an earthly master, as if they were working for Christ (5-8). Christian masters must act with similar honesty and concern towards those who work for them. They must remember that, in the eyes of God, masters are servants and God is their master (9).