What does 1 John 3:6 mean?

Two important truths are revealed in this brief verse. First, John has already defined those who "abide:" believers who walk in fellowship with Jesus Christ. Here, he adds that no one who continually sins does so as a result of a relationship with Christ. The typical interpretation of this passage is that a person who continually or repeatedly sins is an unbeliever, whereas a believer can sin, but only on occasion. While this is possible, the specific context is about the results of a relationship with Christ. True fellowship with Christ cannot result in sin—this is part of John's defense against the claim that the gospel gives people an excuse to do wrong.

The general context of this passage, and the rest of Scripture, is that a believer is marked by a changed life. A believer's life will involve some level of growth, known as "sanctification," and is expected to be noticeably different from that of an unbeliever. Of course, how much a person grows in their relationship is up to them, so a lack of spiritual maturity is in no means a test for salvation.

However, the person whose life does not change—who shows no change from their former life, or a distinction between them and the unbelieving world—reveals he or she has not seen or known Jesus. Though every believer is a work in progress, every believer's life should show a noticeable difference in living a life that becomes more like Christ. If a person's life is no different than that of a non-believer, there is no reason to be confident they are a true believer.