refers to sin in Ephesians, it is normally not for the purpose of developing sin as an independent doctrine. Instead, Paul sometimes refers to sin as that which Christians used to do in the past, or something to put off. His most common purpose for discussing sin is for contrast. In other words, Paul sees sin as the dark side of the Gospel. It serves a purpose beyond itself, namely, to explain the need and glory of God's grace. Thus, a doctrine of sin from Ephesians can be developed with an exploration of the doctrines Paul seems more interested in, such as redemption, sanctification, glorification, or ecclesiology.
The most commonly known reference to sin in Ephesians, and perhaps one of the most well-known in Scripture is Ephesians 2:1. This verse is often used as a foundation texts for doctrines such as original sin and total depravity. Rightly so. Paul's purpose in Ephesians 2:1-3 seems to be to build context for the rest of chapter 2, and what he gives is a bleak description of the human condition. Humanity is a race of spiritually dead creatures, and in this passage Paul blames spiritual death on sin. Most English translations use the word “in” to describe the connection between death and sin, choosing to translate the relationship as locative, as in “And you were dead in the trespasses and sins” (ESV), but the case Paul uses could also be translated as instrumental. In other words, “by means of” would be just as valid of a translation as “in.” It is possible Paul had both meanings in mind here. The point is clear; it is spiritually deadly to sin. Sin and spiritual death are universal. They are the natural course of humanity today, as Paul goes on to explain.
Ephesians 2 tells us more about sin. It explains that the lifestyle of sin is the normal pattern for godless humanity. Paul describes sin and transgression as a walk “according to the course of this world, according to the prince of the power of the air, of the spirit that is now working in the sons of disobedience” (2:2b). Apart from God's intervention, all of humanity, both the individuals and the world system, is walking in spiritual death. This world system of spiritual death is populated by individuals who are “by nature children of wrath.” The whole of humanity follows the satanic pattern of rebellion against God. The future and end of humanity is to fulfill its nature – wrath. The walk of sin is a walk down the road to God's wrath.
In verse 4 Paul reveals his true purpose for discussing sin, both in this section and elsewhere in Ephesians. He brought up sin for context, contrast, and comparison. It seems verses 2:1-3 are in juxtaposition with 2:4-10, and perhaps the rest of the chapter. Instead of being spiritually dead (2:1), those in Christ's church have been given spiritual life (2:5). Rather than walking in transgression and sin (2:1-2), Christians walk in good works (2:10). Where once a Christian conformed to the satanic world order (2:2), he now finds himself walking in righteousness as a part of God's new humanity (2:10, 19). The comparisons go on, but suffice it to say, it seems that Paul's main point is to communicate what it means to be in Christ, and one of his methods is to explain what it means to be outside of Christ. The contrast is stark.
Paul does reference sin in other ways and places throughout Ephesians, though often for the same purpose. Even while he makes more comments about sin in passing, he manages to fill in more of the picture of Christless humanity. In 4:17-24 there is a similar contrast between the old and new humanity. Here Paul describes the “Gentile . . . walk” in terms of the heart and mind. Unbelievers live in a futility of mind, a darkness of understanding, ignorance, hard-heartedness and unbelief, and are ultimately godless. This is a description of the inner-life (or lack thereof!) of a spiritually dead person. Again it is in contrast to the new life in Christ. Paul's basic point is simply stated: “So this I say . . . walk no longer [like that, but] be renewed in the spirit of your minds, and put on the new self, which in the likeness of God has been created in righteousness and holiness of the truth.”
There are also implications regarding sin that can be drawn from other parts of Ephesians. For example, Paul refers to Christ's sacrifice several times throughout Ephesians (e.g. 5:2). A sacrifice implies atonement, or at least propitiation of wrath. This raises the question, wrath against what? This has already been seen in Ephesians 2:3. Paul also speaks of a spiritual struggle against wicked forces in 6:10ff. The implication here is that sin is not limited to humanity, but has infiltrated the heavenly realm as well. This does not necessarily imply a dualistic universe, but it does mean humans are not the only spirit beings engaged in sin. Obviously sin is also implied by many of the imperatives throughout the letter. For example, 5:18 says “do not get drunk with wine.” Implicit in the command is that drunkenness is sinful, not to mention that disobeying an apostolic command is sinful in its own right.
One of the major themes in Ephesians is the church's union with Christ. Paul uses several metaphors to explain the intimacy and strength of this union, including calling the church in Christ, a temple of God built on Christ, and especially Christ's body. This presents an interesting question, namely, how can Christ's body participate in sin? This seems almost paradoxical, yet it is clearly possible. Christians would not need to be exhorted not to walk in sin unless it was possible for them to. Paul does not seem to be interested in this conundrum, however. Rather than address the issue of sin in Christ's body as untenable or paradoxical, he leverages the theological concept to motivate practical holiness. He commands love and unity based in part on the church being one body in Christ (4:2-4). In 5:25ff Christ is said to love the church in order to sanctify her, even as a man loves his own body and cares for it. 4:17, which begins an exhortation to righteous living, actually starts with the word “so,” basing the proceeding exhortation on the immediately preceding doctrine. The doctrine preceding 4:17 is the metaphor of the church as the growing body of Christ.
Ephesians 4:1 summarizes what Paul does with the paradox of sin and Christ's body, and indeed Paul's reason for any of the times he brings up sin in this letter. “Therefore I . . . implore you to walk in a manner worthy of the calling with which you have been called.” Sin in Ephesians is truly a negative concept. It is something Christians must not participate in, something they must put off, something they used to walk in, but must walk in no more. It now serves as a narrative and theological context for the glories of God's grace in the Gospel, as the Christian looks back to where he came from, only to gain fresh inspiration to keep walking worthy of his new calling in Christ.