"Love not the world, neither the things that are in the world." (1 John 2:15)
We must be wary of the world's "things," because we are "in the world" not "of the world" (John 17:11-16). The command in our text is that we are not to love the world or its things, not that we should remain blissfully ignorant of them. We are to be "wise as serpents, and harmless as doves" (Matthew 10:16).
There are big things of the world like nations and kingdoms (Matthew 4:8; Luke 12:30) as well as cares and riches (Mark 4:19) which can sap our focus and drain our loyalties. And there are "rudiments" and "elements" (Colossians 2:20; Galatians 4:3) that can twist our thinking and "spoil" us (Colossians 2:8).
We are warned that friendship with the worldly lifestyle and that which espouses the "things" of the world, makes us an "enemy of God" (James 4:4). That is because such people embrace the "spirit of the world" and not "the spirit which is of God" (1 Corinthians 2:12). Those people speak about the things of the world, and the world listens to them (1 John 4:5).
God's people may be "base" and "weak"--even "foolish" in the eyes of the world (1 Corinthians 1:27-28). Since the great Creator God has chosen us out of the world (John 15:19), it should not surprise us that the world "hates" those who belong to the Lord Jesus (John 17:14). Hence, the ungodly passions that drive the ungodly behavior of the world, "the lust of the flesh, and the lust of the eyes, and the pride of life, is not of the Father, but is of the world" (1 John 2:16).
Those passions and the people who embrace them will "pass away." But "he that doeth the will of God abideth forever" (1 John 2:17). HMM III