John is not the only apostle who called upon the children of God to keep themselves from being spiritually contaminated by the world. James urges us "to keep oneself unspotted from the world" (James 1:27). The apostle Paul makes a strong appeal in Romans 12:2, saying, "And do not be conformed to this world, but be transformed by the renewing of your mind, that you may prove what is that good and acceptable and perfect will of God."
This world is not God's world! Some have such a difficult time grasping the practical ramifications of this concept, perhaps because we think of God as Creator, Owner, and Ruler and marvel at the staggering beauty of what He has made. In that sense it is His world.
Nonetheless, the systems that operate our cultures are not His. The Greek word translated "world" in I John 2:16 is kosmos, which has a moral connotation and means "the world apart from God." William Barclay in his commentary on this verse writes, "To John the world was nothing other than pagan society with its false values and its false gods" (p. 56).
The world's systems generate and sustain our government and politics, entertainment, fashion, religion, business ethics, medicine and health care, culinary tastes, social programs and institutions, education, science and technology, economics, and use of power. The world's systems have formed much of our belief systems and attitudes, and these in turn have shaped our conduct.
These are the things we must overcome. And this world and its systems are so appealing! But God says not to waste our love on them because they have no future! In fact, this world is so bad that other prophecies show the whole thing will be destroyed and replaced when God invokes the restitution of all things (II Peter 3:10-11; Revelation 21:1).
The basic reason all must be destroyed is because at its very foundation is a destroying and antagonistic spirit, Satan the Devil, the god of this world. Henry David Thoreau grasped an important principle when he stated, "An institution is but the lengthened shadow of one man." As Jesus phrases it, "A corrupt tree cannot bring forth good fruit" (Matthew 7:18). Satan is a destroyer, and his way is at best a bad mixture of good and evil. James confirms this when he asks this rhetorical question, "Does a spring send forth fresh water and bitter from the same opening?" (James 3:11).