"For by one offering he hath perfected for ever them that are sanctified." (Hebrews 10: 14)
This verse, this promise, is hard for some people to accept.
We are perfected. How? In our actions.
No, because if that were the case, then we would not have to be transformed from glory to glory:
"But we all, with open face beholding as in a glass the glory of the Lord, are changed into the same image from glory to glory, even as by the Spirit of the Lord." (2 Corinthians 3: 18)
"1Behold, what manner of love the Father hath bestowed upon us, that we should be called the sons of God: therefore the world knoweth us not, because it knew him not. 2Beloved, now are we the sons of God, and it doth not yet appear what we shall be: but we know that, when he shall appear, we shall be like him; for we shall see him as he is." (1 John 3: 1-2)
We are born again in our spirit, and even if our outside is growing old, on the inside we are renewed from day to day:
"For which cause we faint not; but though our outward man perish, yet the inward man is renewed day by day." (2 Corinthians 4: 16)
So, we are made righteous by our position, because God the Father has seated us in heavenly places in Christ Jesus.
He sees us, and He sees His Son, because we are in Him today.
"Herein is our love made perfect, that we may have boldness in the day of judgment: because as he is, so are we in this world." (1 John 4: 17)
Christ lives in us, and He is our hope of glory (Colossians 1: 27), and as we grow in grace and knowledge of Him, His glory is revealed in us and through us:
"But by the grace of God I am what I am: and his grace which was bestowed upon me was not in vain; but I laboured more abundantly than they all: yet not I, but the grace of God which was with me." (1 Corinthians 15: 10)
He has perfected us forever, and He is bringing out this perfection in us today:
"Being confident of this very thing, that he which hath begun a good work in you will perform it until the day of Jesus Christ:" (Philippians 1: 6)