As Christians, we certainly don't want to ~ and try not to ~ fall short of God's glory (sin) any longer.
And this is certainly the exhortation, from Jesus to the woman at the well in John 4, and the woman guilty of adultery in John 8, and from John in 1 John 2, and many other places ~ to "lay aside sin which clings so closely," as the writer of Hebrews says in chapter 12.
But though we don't want to sin and though we strive against sin, we know we still will sin ~ not willingly, but we will still do the things we know we know we ought not to do, and we will not do the things we know we should do, just like Paul in Romans 7. At any point in time, even after we have been born again of the Spirit, if we say we have not sinned, we make Him a liar, and His word is not in us (1 John 1:9).
But thanks be to God, for those of us in Christ, Just as Paul says in Romans 8:1, we know that for us, there is no more condemnation for sin, and that nothing can separate us from the love of God in Christ Jesus. And when (not if) we do sin, we can be sure that when we confess our sin, God is faithful and just to forgive us our sins and to cleanse us from all unrighteousness ~ because we are in Christ (1 John 1:8).
Once God has saved us, He will not "unsave" us. But this most certainly does not mean, somehow, that "hey, now, disobedience, or sin, is now sanctified or okay" in any way. Certainly, that is not the case. Even so, though we still fall short (see above), thanks be to God, those whom He foreknew ~ foreloved ~ he also predestined to be conformed to the image of his Son... (a)nd those whom He predestined he also called (or calls at some point), and those whom He called (calls) He also justified (justifies), and those whom He justified (justifies) He also glorified (glorifies; will glorify) (Romans 8:29-30). The gifts and the calling of God are irrevocable (Romans 11:29).
Grace and peace to all.