What does Ephesians 4:17 mean?

In Ephesians 4:1–16, Paul focused on Christians living lives worthy of our calling by God. Now Paul transitions to a new section in verses 17–32. He contrasts the new life believers have in Christ, as opposed to the "old life" of the world. Paul's introduction notes how directly and seriously he intends these instructions to be taken. The reference to speaking "in the Lord" makes his words stand out.

Paul instructs the Ephesians not to share in the kind of immoral lifestyle which non-believers follow. The Ephesian Christians were mostly Gentiles, in the sense of being non-Jewish: they were not descendants of Israel. Symbolically, "the Gentiles" mentioned in this context are those people who are separated from God. They are the unsaved. As saved believers, the Ephesians were once "spiritual" Gentiles, but no longer. Paul's point here is that believers cannot continue to live as unbelievers and expect to please God.

Unbelievers have a very different mindset from those who are saved by Christ. Paul describes that approach as "futile." Ultimately, the goals of unbelievers have no point or purpose. In contrast, believers live with a clear purpose: to glorify God through making disciples. This includes personal spiritual maturity (Ephesians 4:13), serving others (Ephesians 4:12), evangelism, and worship. These activities are not designed only for individuals but for the church as a family.

The ancient mindset was more collective than individualistic as in Western cultures today. Most activities were centered around families and groups, including spiritual growth.