In the last section, John addressed the spiritual state of the church he was writing to and encouraged them on in continued growth. He had already talked about the importance of loving one another. Now he turns his attention on what they were not to love and the dangers of this world.
v15. While Christians are required to “love their brother and sister,” on the other hand they are forbidden to “love the world or anything in the world.” This is a blanket statement that will be clarified shortly, but its force should not be diminished. Taken seriously, this command is as hard to keep as the positive command to love each other (and maybe for the same reason!). It’s easier, though, when we realize how important it is. John tells his readers that if they do love the world, “then the love of the Father is not in him.” How can we be in fellowship with God if “the love of the Father” is not in us? To put it in simple, stark terms, we either love each other and so are in fellowship with God and one another, or we love the world and are not in fellowship with God (and so not with one another, either).