If we want to thrive in our faith and continue to grow in God’s grace we must always be engaged in a fight against sin. The apostle Peter writes, “Beloved, I beg you as sojourners and pilgrims, abstain from fleshly lusts which war against the soul” (1 Pet. 2:11).

The battles we often face present themselves as coming from outside of us. Christians have identified our three enemies as the world, the flesh, and the devil. It’s easier to see our exterior enemies and focus on them—the world and the devil. But in order for us to ever be overcome by these, we have to have already given in to the flesh. This why Jesus said that defilements come not from the outside, but from within.

Rules to govern external influences can be helpful—movies, books, music, etc., but only because we are winning the war against our fleshly lusts. We must always remember this is the fundamental battle. To stop fighting it is in principle to give in, and as soon as a Christian does this, it’s only a matter of time before other battles are lost. When we get into significant or scandalous sin, it’s easy to see the final temptation. A man who took the opportunity to steal a million dollars from his company obviously wanted the money, but a long time before that he was some mixture of envious, covetous, lazy, entitled, discontent, resentful, unthankful and so on. He gave in to these fleshly lusts a long time before he touched any dough.

Christians have been freed from the reign of sin that completely dominates them, but they still have remaining lusts that wars against the soul. Fighting against these is constant. Paul encourages, “Therefore put to death your members which are on the earth: fornication, uncleanness, passion, evil desire, and covetousness, which is idolatry” (Col. 3:5). Mortify these, and live free.