Don't love the world, neither the things that are in the world. If anyone loves the world, the Father's love isn't in him.
neither the things that are in the world: John forbids a course of action for the Christian that sets a high value on the evil world-system in general or on any part of that system specifically. One might reject the world in general but reserve some secret vice or favorite sin. The love of money was the one reservation in the heart of the rich young ruler that robbed him of his relationship with Jesus (Luke 18:18-30). In general, his life was exemplary; notwithstanding, "the things that are in the world" caused him to abort his quest for eternal life. Every wrong linked with the world must be broken in order for our love for the Father to remain pure and untainted.