18 We know that everyone who has been born of God does not keep on sinning, but he who was born of God protects him, and the evil one does not touch him.19 We know that we are from God, and the whole world lies in the power of the evil one.20 And we know that the Son of God has come and has given us understanding, so that we may know him who is true; and we are in him who is true, in his Son Jesus Christ. He is the true God and eternal life. 21 Little children, keep yourselves from idols.
As John finally concludes his letter he reminds his readers of four key points: we don’t have to be the way we have always been, this world is not our home, truth is found in God and, anything that is not from God is against Him.
First of all, we don’t have to be the way we have always been. In fact, we should not be. “Everyone who has been born of God does not keep sinning (v. 18).” If we have experienced Christ’s love and abide in Him we will “walk in the way He walked (2:6),” and sinful patterns and practices from the past will not define us. God so wants us to live new lives that He personally protects us, from sin and from the evil one who would tempt us and who seeks to do us harm.
Secondly, John reminds his readers that this world is not our home. In chapter 2, verses 15-17, he wrote, “all that is in the world—the desires of the flesh and the desires of the eyes and pride of life—is not from the Father but is from the world.” That anything should come from a source other than the Father should be reason enough for us to avoid it, but John makes clear here that the world is not neutral, but “lies in the power of the evil one (v. 19).” This is why the world hates us (3:13), this is why it often feels like a hostile, unfriendly place.
About Christ, Who died on the cross so that we might live, John says he has not just given us salvation, but understanding. That understanding teaches us about the world and how we are to live in it: “His anointing teaches you about everything, and is true (1:27).” But John’s emphasis here is that the understanding Christ gives us serves an even greater purpose, to know Him and His truth. Knowing God, we know everything else, but not only do we know Him, we are in Him. This vital relationship gives us comfort, hope and purpose, not only for this life, but for eternity.
Finally, John’s last word is that we must keep ourselves from idols. This may seem like a problem of the ancient world and not one we need to worry about, but we must remember there is an evil one with power over the world and he, and the world he governs, hates us. There is only one true God, but there are millions of false one—idols—and the evil one uses whatever means he can to turn us away from light to darkness.