Frenemies

And then he added, "It is what comes from inside that defiles you. For from within, out of a person's heart, come evil thoughts, sexual immorality, theft, murder, adultery, greed, wickedness, deceit, lustful desires, envy, slander, pride, and foolishness. All these vile things come from within; they are what defile you."
—Mark 7:20-23

Three enemies that we contend with as Christians are the world, the flesh, and the devil. The world with its allure is the external foe. The flesh with its evil desires is the internal foe. And the devil with his enticements is the infernal foe. These are what we deal with on a daily basis.
The problem is that we become frenemies with the world. A frenemy is someone whom you normally don't get along with, but if it serves both of your purposes, you temporarily become friends. Or, it might be a love-hate relationship: You are on. You are off. You are on. You are off. Then again, it might be a description of a relationship that is poisonous, and whenever you are around that person, it drags you down spiritually. Thus, he or she becomes a frenemy.
Some of us have become frenemies with the world. When the Bible speaks of the world, it doesn't mean the planet Earth. It is speaking of a pervasive philosophy that infects everything, everywhere. We are told in 1 John 2:16, "For the world offers only a craving for physical pleasure, a craving for everything we see, and pride in our achievements and possessions. These are not from the Father, but are from this world."
The world is enticing. But for its pull to work, we must desire what it is offering. Jesus said, "It is what comes from inside that defiles you" (Mark 7:20). Why do we do the stupid stuff that we do? It is just our nature—our human, sinful nature. We have to be aware of the combustible, evil, sinful nature that is inside every one of us. The answer is not within; the problem is within. So when we give in to temptation, we have ourselves to thank.