Fix Your Eyes On the Cross of Christ
There is no silver bullet for killing indwelling sin. Too many are its manifestations, too crafty its schemes, too tight its hold on the wicked crevices of our sinful hearts. But even so, there is one uniting principle under which all striving for holiness, all mortification of sin, all thirsting for righteousness, happily dwells. John Owen explains:
Would we not be enticed or entangled? Would we not be disposed to the conception of sin? Would we be turned out of the road and way which goes down to death?—let us take heed of our affections; which are of so great concern in the whole course of our obedience, that they are commonly in the Scripture called by the name "heart," as the principal thing which God requires in our walking before him. And this is not slightly to be attended to. Says the wise man, "Keep your heart with all diligence" (Prov 4:23) or, as in the original, "above" or "before all keepings"—"Before every watch, keep your heart. You have many keepings that you watch unto: you watch to keep your lives, to keep your estates, to keep your reputations, to keep up your families; but," says he," above all these keepings, prefer that, attend to that of the heart, of your affections, that they be not entangled with sin."
There is no safety without it. Save all other things and lose the heart, and all is lost—lost unto all eternity. You will say, then, "What shall we do, or how shall we observe this duty?"
In general. … Fix your affections upon heavenly things; this will enable you to mortify sin; fill them with the things that are above, let them be exercised with them, and so enjoy the chief place in them. They are above, blessed and suitable objects, meet for and answering unto our affections—God himself, in his beauty and glory; the Lord Jesus Christ, who is "altogether lovely," the "chief of ten thousand" [Song 5:16,10]; grace and glory; the mysteries revealed in the gospel; the blessed promised thereby. Were our affections filled, taken, up, and possessed with these things, as it is our duty that they should be—it is our happiness when they are—what access could sin, with its painted pleasures, with its sugared poisons, with its envenomed baits, have unto our souls? How should we loathe all its proposals, and say unto them, "Get you hence as an abominable thing!" For what are the vain, transitory pleasures of sin in comparison to the exceeding recompense of reward which is proposed unto us?
…As to the objects of your affections, in a special manner, let it be the cross of Christ, which has exceeding efficacy toward the disappointment of the whole work of indwelling sin: "God forbid that I should glory, save in the cross of our Lord Jesus Christ, whereby the world is crucified to me, and I unto the world" (Gal. 6:14). The cross of Christ he gloried and rejoiced in; this his heart was set upon; and these were the effects of it—it crucified the world unto him, made it a dead and undesirable thing. The baits and pleasures of sin are taken all of them out of the world, and the things that are in the world—namely, "the lust of the flush, the lust of the eyes, and the pride of life." …If the heart be filled with the cross of Christ, it casts death and undesirableness upon them all; it leaves no seeming beauty, no appearing pleasure or comeliness, in them. Again, says he, "It crucifies me to the world; makes my heart, my affections, my desires, dead unto any of these things." It roots up corrupt lusts and affections, leaves no principle to go forth and make provision for the flesh, to fulfill the lusts thereof.
Labor, therefore, to fill your heart with the cross of Christ. Consider the sorrows he underwent, the curse he bore, the blood he shed, the cries he put forth, the love that was in all this to your souls, and the mystery of the grace of God therein. Meditate on the vileness, the demerit, and punishment of sin as represented in the cross, the blood, the death of Christ. Is Christ crucified for sin, and shall not our hearts be crucified with him unto sin? Shall we give entertainment unto that, or hearken unto its dalliances, which wounded, which pierced, which slew our dear Lord Jesus? God forbid! Fill your affections with the cross of Christ, that there may be no room for sin. The world once put him out of the house into a stable, when he came to save us; let us now turn the world out of doors, when he is come to sanctify us.
Owen, John. Indwelling Sin, Part 2: The Power and Efficacy of Indwelling Sin. Overcoming & Temptation. Edited by Kelly M. Kapic and Justin Taylor. Crossway Books, 2006. pg. 331-332.