The opening word of the passage (in Greek, dio, "for this reason") is a reminder to situate these instructions in their context in Ephesians.
The immediate context recalls the transformation of those who are in Christ: "You were taught to put away your former way of life... and to be renewed in the spirit of your minds and to clothe yourself with the new self" (4:22-24). In verse 25, the words "putting away falsehood" echo the putting away of one's former way of life. The new life experienced in Christ is meant to have far-reaching effects, and it is precisely those effects that are elaborated in 4:25-5:2.
In the larger context of the letter, the gift of God in Christ has brought about reconciliation of Jews and Gentiles, creating one community, which the author describes metaphorically both as Christ's "body" (e.g., 1:22-23) and as a building (2:21-22). Both metaphors are pertinent to the language of this passage, which reminds the reader that "we are members one of another" (4:25) and emphasizes "what is useful for building up" (4:29; cf. 4:12, 16). The behavior of the faithful should reflect the grace of God in Christ, and should benefit the community as a whole.
The instructions that follow focus on the power of speech. The writer cautions the reader about anger. Verse 26 quotes Ps 4:4 (LXX): "Be angry but do not sin." The phrasing is not meant as an exhortation to anger, but is more likely conditional: "If you are angry, do not sin." Anger is understood as a normal part of human emotional experience, yet also as an occasion for temptation (making "room for the devil," verse 27). The solution is the limitation of anger: "Do not let the sun go down on your anger" (verse 26). Living with anger for an extended period is likely to lead to sin. In a later verse, the writer uses five different words that all indicate some variety of anger, perhaps in an order that suggests escalation: "bitterness and wrath and anger and wrangling and slander" (verse 31). All these are to be put away, as all represent a threat to the growth of the body.
The church has often had difficulty teaching about anger. While this passage and others sound an important cautionary note about the effects of anger on the community, too often the message has been that anger should be swallowed or ignored. The irony is that, in trying to act like "good Christians" who do not experience anger, anger that does exist often goes underground where it festers and creates more serious problems. The results can be easy to spot. In many congregations, what began as a small incident sometimes lingers for years because of the anger that exists on either side, anger that is never expressed. The situation applies to individuals within congregations as well as to conflicts between groups. Pastors and other leaders in the church often exacerbate the problem by skirting around the issue in order to avoid conflict themselves. Yet the "peace" that results is not rightly called "peace." Sometimes it is "détente," but other times it is barely contained hostility.
The passage itself contains a helpful corrective to this, in the opening maxim, "let all of us speak truth to our neighbors" (verse 25). The wording here reflects the earlier language of the chapter, which is also helpful: "Speaking the truth in love, let us grow up in every way into him who is the head, into Christ" (4:15). Speaking the truth in love can be a healing strategy in a situation of anger. Such speech identifies the situation for what it is, calling others to account, giving voice to feelings, and confessing one's own participation in wrong-doing. When anger is the framework for such truth telling, the division of the body often results. Yet when love is the framework, healing can result. Even situations that seem intractable or unpardonable are sometimes transformed by this approach.
Other language within the passage helps to flesh out the notion of speaking the truth in love. Believers are to speak only "what is useful for building up, as there is need, so that your words may give grace to those who hear" (verse 29). The reader is also exhorted to be kind (or "generous"), tenderhearted (or "compassionate"), and forgiving of one another (verse 32). Just as the list related to anger in verse 31 may increase in intensity, so also the attributes of verse 32 may be sequential, with a generous heart giving way to compassion, leading toward true forgiveness.
The ultimate call is to imitate both God and Christ (5:1-2), whose love has been central to the message of Ephesians (cf. 2:4; 3:19) and is meant to characterize the life of faith (1:4; 3:17; 4:2, 15, 16). Although the command to "imitate" in the New Testament more commonly refers to the imitation of Christ or Paul (cf. 1 Corinthians 11:1; 1 Thessalonians 1:6), the call to imitate God is consistent with the viewpoint of Ephesians. Just as the Christian community was "created according to the likeness of God in true righteousness and holiness" (4:24), so here the "new self" of the believer is formed by the imitation of God. God's love and reconciliation brought about though Christ should be formative of Christian life.
Even with the transformative effects of the love of God, the writer of Ephesians recognizes that sin does not disappear. The persistence of sin is not an indictment of the transformation itself but a reflection of human frailty. Many of the New Testament writings deal at length with the persistence of sin within the body of Christ. The language of 4:28, "Thieves must give up stealing" is a reminder that even thieves are to be found within the body--along with people doing every other act that is clearly identified as sin by both the Old and New Testaments. Ephesians provides an opportunity to address these practical and spiritual concerns in a way that "promotes the body's growth in building itself up in love" (4:16).