As children of God, we are known for one thing, or we should be known by one thing, and that is we should love or have love for each other. This is how we know who are children of God; that's what separates us from children of the evil one. John makes it clear in our text when he says, "Anyone who does not do what is right is not God’s child, nor is anyone who does not love their brother and sister." Doing what is right comes down to loving our brothers and sisters.
Why are we so wicked to each other at times? It's not because it is warranted. It's because we have become children of the evil one, and the love of God is not in us. When God's love is in us, we see it by how we love and treat each other. In other words, by their fruit, he shall know them. It should be evident with the fruit of the Spirit. And the Bible tells us that the fruit of the spirit is Love. That's it. At the foundation of the fruit of the Spirit is Love. Love is the foundation on which the fruit of the Spirit is built.
Therefore, as children of God, we should love one another. Now, this is not a request, it's not a suggestion, it is a command, and if you are a child of God and love God, the command is to love each other. Such love commands kindness, goodness, and self-control, among other things. Love is always more powerful than evil. Let's walk in love together as children of God so we can inherit eternal life and help our brothers and sisters along the way.