The distinction between the first quality, “reject sin,” and this one, “love not worldliness” may seem subtle. However, John is not repeating himself. Worldliness is not sin, but rather the tendency of the world to embrace and relish the temptation that leads to sin.
Here, John describes worldliness in more detail:
“For all that is in the world, the lust of the flesh and the lust of the eyes and the boastful pride of life, is not from the Father, but is from the world.”
What he is describing is the rather narrow range of means by which temptation offers sin to us. Humanity is prone to stumbling when it is offered things that are physically satisfying, aesthetically pleasing, or that whisper encouragement to our vanity. It is a universal truth that we see throughout history.
Right from the start, Adam and Eve are tempted to rebel against God by seeing that the forbidden fruit is: “…good for food, and that is was a delight to the eyes, and that the tree was desirable to make one wise.” Satan used the same ploys when attempting to temp Jesus in the wilderness. He offered Him relief for His hunger, the world and all its glory, and an opportunity to reveal Himself as the Savior of mankind.
John is wise in encouraging us to not just reject sin, but to not become fond of the things in the world that tempt us. It is likely that the believers of his day were similar to those of our time. We are great at dancing on “the line.” We love to flirt with sin, to do as much as we can get away with without giving in to sin. The problem is that the line become quite blurry the closer one gets to it. What we want to avoid here are two things: the love of “nearly sinful things,” and the legalism that seeks to protect us from them.
Legalism is the cousin of loving worldliness. Adam tried to protect Eve from sin by adding rules to the command that God had given. He told her they could not touch the tree. It likely only made her more susceptible to sin, when touching the tree had no harmful affect.
Instead, John wisely encourages us to not love worldliness. Temptation makes sin seem enticing; we need to recognize its lie. Sin is not the appealing joy that it seems to be. Instead of getting as close to sin without sinning as possible; we should long for and appreciate the good things in life that God offers us. When we do that, we discover that God offers us truth where temptation offers lies. He provides us with all our physical needs in a way that He has designed them to be met. He has created so much beauty for us to enjoy that glorifies Him. And He gives us true fulfillment being the people He has created us to be.