We need to back up to 1 John 2:18-19 to get the issue that John is concerned with. Keep in mind that John is writing in his old age, probably in the same decade as his writing of the Gospel and Revelation. He is also writing to people he knew years ago, but we do not know what congregation this was intended for. He may have intended for it to be circulated because many congregations were dealing with the same issues.
Children, this is the Last Hour. You have heard that an Anti-Messiah is coming; and in fact, many anti-Messiahs have arisen now — which is how we know that this is the Last Hour. They went out from us, but they weren’t part of us; for had they been part of us, they would have remained with us. CJB
In the closing years of the First Century, congregations were battling against Gnosticism and other heresies. They talk about the Messiah, but they don’t know the Messiah. They teach that Jesus was not a real human; that his teachings can only be understood by joining a secret society and experiencing their mystical ceremonies.
John says, ‘don’t fall for that snake oil.’ They say turn right, or left, or something else that is wrong.
If you know Jesus, Consider the incredible love that the Father has shown us in allowing us to be called “children of God”—and that is not just what we are called, but what we are. Phillips
In case you missed it the first time, Beloved, we are God’s children now. ESV But what John writes next you need to read carefully. We don’t know what we shall become in the future. We only know that, if reality were to break through, we should reflect his likeness, for we should see him as he really is! Phillips For reality, read, when Christ appears. NIV
What John is saying is that those of us who believe in him and strive to follow in his steps will recognize him while non-believers will not know who he is. Becoming a part of the body of the Messiah means that we will also rise up from the grave. Death cannot hold us.
All who have this hope in him purify themselves, just as he is pure. NIV John is not saying that we can become pure by our own efforts. He is only saying that we daily strive to drive away sins so that we can feebly reflect his pure light into the world. We must accept that we are mirrors covered in dirt, with cracks and broken edges, but we work to keep ourselves as clean as possible.
Everyone who commits sin breaks God’s law, for that is what sin is, by definition—a breaking of God’s law. Phillips John now looks at the opposite position. Followers of Jesus seek to obey God’s Law. People who reject Jesus—and God—live in sin. (Paul has a lengthy argument in his letter to the church in Rome explaining why Jews who don’t believe in Jesus are still within the Covenant if they do not reject God.)
Children, don’t let anyone deceive you — it is the person that keeps on doing what is right who is righteous, just as God is righteous. CJB John’s final words in today’s reading.
Be righteous and do good.