Those in Christ are not lowly sinners saved by the grace of God. We are holy, righteous, sanctified saints who have been saved by the grace of God and have become the righteousness of God (2 Cor 5:21) and in fact been perfected forever! (Heb 10:14).
We have become "one spirit with Him" (1 Cor 6:17) and we have become "partakers of the divine nature" (2 Peter 1:4). Romans 5:1 says that we (saints) have peace with God, having been justified by faith. We have been justified. (We are justified). We are righteous. We are holy. We are perfected.
All of this is due to the gift of God. It's not our gift to Him and it's not our work for Him. We could never attain any of this through our own effort, even with "God's grace" added to "our efforts." It all had to be a gift, and God did give it all to us as a gift.
Notice even in Romans 7 (and elsewhere), the struggle isn't MINE. The battle within is between the Spirit and the flesh. I am neither the Spirit, nor am I the flesh. I am a perfected, righteous, holy, spotless saint.
ALL our sin has been cleansed and taken away by nothing less than the blood of Jesus. To live as if we are lowly sinners is to spit on the work of Jesus. "It is finished!", he cried. He became sin for us so that we might become the righteousness of God in Him.
The problem isn't that we're lowly sinners. The problem is that we're a royal priesthood who don't understand that we're a royal priesthood! We're righteous, holy people who have become one spirit with God, who don't understand that we're righteous, holy people who have become one spirit with God! We think that because we still miss the mark (in our behavior), THAT defines us. But sin no longer defines us. Sinful behavior is a result of not living as who we truly are. But it never changes who we truly are. We remain the righteousness of God because He has given us His very own righteousness as a gift. Not because we deserved it. Not because we earned it. Not because we stopped sinning. But because of the sacrifice of Jesus. Because of His blood and nothing less.
We need to live in the reality of what He has done for us and who He has made us to be. We are new creations!