Lust is a powerful and relentless enemy. But it is impossible for someone feeling the scourge of lust’s assaults to ready himself for battle without the right equipment. The first piece of weaponry we must acquire is a sound grasp of our justification. To make genuine progress in our fight against illicit sexual desires and sexual sin, we must begin with the firm conviction that we are not justified by the progress we make in our fight against illicit sexual desires and sexual sin. No work will justify us, even the work of battling lust. That’s why Paul writes, “Now to the one who does not work but believes in him who justifies the ungodly, to him it is counted as righteousness” (Rom 4:5).
Our right standing before God was established for all eternity at the moment we placed saving faith in Jesus Christ, and our right standing with God is grounded in the finished work of Christ (Rom 3:26; 5:1), not our ongoing work of sanctification (i.e, growing in Christlikeness). At the moment we are justified, we are still ungodly, as Paul says in the verse above. Sinner, this is the gospel: It is the ungodly who are justified, not those who have achieved a modicum of self-made progress in their battle against sexual sin. If we cling to some measure of self-wrought purity as the basis for our right standing with God, we will never be justified and never actually experience true growth in sexual holiness. We must first come to Christ empty-handed, ungodly, and as mere recipients of grace. Then, having been justified by faith in Christ apart from our works and forever free from the condemnation of the law (Rom 8:1) and regenerated by God’s Spirit (Titus 3:4-7), we labor with joy to put off the sins that destroy our soul and put on the spiritual qualities that please the Lord (Eph 4:22-23).
Our labor against lust is not a work we do to get God to forgive us or like us. If you’ve turned from your sin and trusted in Christ alone for your salvation, God already accepts you as his beloved child because of the work of his Son (Col 1:14). We’ve been warmly welcomed into his family, never to be lost or cast out (John 6:37; Rom 8:39). We strive diligently for sexual purity not to get God to work in us, but because God is already at work in us (Phil 2:12-13).
Indeed, a person cannot make one step in genuine, heart-level change when it comes to sexual purity unless they are justified by faith in Christ. Only sin that has been forgiven is sin that can be put to death, and only those who have received the Holy Spirit by faith in Christ possess the power to root out lust (Rom 8:1-17; Gal 5:16; Col 2:13; 3:1-10).
These are vital truths that we must take deep into our hearts so that we don’t stifle the Spirit’s work in our life. When the Galatian Christians started to believe that obedience to the Old Covenant law needed to complement their faith in Christ in order to ensure they were right with God, their faith in Christ was clouded, which clogged the Spirit’s flow through their lives (Gal 3:1-5). Now, without recourse to the Spirit’s power, the Galatian believers were susceptible to being overrun by the works of the flesh (Gal 5:16-21). Their battle against sin was weakened because they allowed a basic error concerning their justification to creep into their hearts and infect their faith with a deadly toxin.
The first tactic in our strategy to grow in sexual purity, therefore, is to fight from our justification, and not for it. We are justified by faith in Christ alone (Gal 2:16). With this glorious truth now embedded in our souls, we take aim at lust with the confidence that God is for us, not against us (Rom 8:31) and that he has given us everything we need to make progress in this great yet temporary battle (2 Pet 1:3-5). It is also a truth that we must preach again and again to ourselves, and get ourselves around people who constantly preach this truth to us.
As we will see with other tactics, preaching the truth of justification to ourselves should not lead us to a kind of moral laxity or indifference toward repentance. We are called to strive to grow in holiness (Heb 12:14). A true understanding of what God did when he justified us doesn’t lead us to ignore sin or become careless about repentance. May it never be, Paul responds to the person who suggests that, now that we are freely justified and secure in Christ, we can sin all the more so that God’s grace will be magnified (see Rom 6:1). No, the doctrine of justification, genuinely embraced, leads to a pursuit of holiness.
Nevertheless, Godward holiness cannot be achieved unless a person begins on the right footing, nor can progress be maintained if a Christian becomes confused about what keeps them right with God. Furthermore, when we sin (and we will, 1 John 1:9), we need the sure confidence that we haven’t undone our justification so that we won’t try to re-establish our right standing with God by our works. That’s why we start with the doctrine of justification and continually remind ourselves of it in the fight for purity.