One of the most difficult pairings in the Christian life is resting in the forgiveness and grace of God without giving up on the fight for holiness (“…without which no one will see the Lord” — Heb. 12:14). I found help on this several years ago in studying Romans 7:17 in which Paul is speaking of doing “what he does not want,” after which he says, “now it is no longer I who do it, but sin that dwells within me.”
In that distinction — between the sin Paul commits and his true identity — is the freedom to move from being a sinner to being “a new creation in Christ” (2 Cor. 5:17). Here’s Paul’s doctrine of new creation in context: “if anyone is in Christ, he is a new creation. The old has passed away; behold, the new has come. All this is from God, who through Christ reconciled us to himself and gave us the ministry of reconciliation; that is, in Christ God was reconciling the world to himself, not counting their trespasses against them, and entrusting to us the message of reconciliation.”
Once we begin to think the way Paul does, sin no longer has the power to threaten who we are. In our sin, especially old, habitual sins, the enemy is always whispering to us: give up, this is who you really are. But Paul’s response in Rom 7:17 is: no it’s not. I am a new creation in Christ. The old has passed away; behold, the new has come.
In certain moments, when I’m on the precipice of despair over some sin, I will simply say that to the Lord: this is not who I am. What that keeps me from doing is floundering in discouragement, standing instead on the finished work of Christ who has reconciled the world to himself, not counting our trespasses against us. “For freedom Christ has set us free” Paul says in Gal 5:1. Technically he’s speaking of circumcision and the Ceremonial Law, but by extension he’s also speaking of the condemnation brought by the law. The blood of Christ preaches a better word: delight in the law of God in your inner being, and remember there is therefore now no condemnation.