Heb 7:19 For the law made nothing perfect, but the bringing in of a better hope did; by the which we draw nigh unto God.
Nope.
Three things:
1) That's not what the text states.
Heb 7:11 - The Mosaic law was based on the Aaronic priesthood, which was required for the law's administration.
Heb 7:12 - With a change in the priesthood, the law no longer had a basis and was necessarily changed.
Heb 7:13-17 - Explains the existing system was to give way to the perfection of Melchizedek's priesthood.
Heb 7:18 - The law was set aside (disannulled) because it was "weak and useless (unprofitable)"
Heb 7:19 - to make perfect (righteous), and a better hope is introduced which did.
That is not a description of the Aaronic priesthood law.
That is the NT description of the Mosaic law (Ro 8:3; Heb 10:1-4), on which the Mosaic (old) covenant was based (Heb 7:11).
And you base the entire point on the statement "The Mosaic law was based on the Aaronic priesthood, which was required for the law's administration." I would see some scripture to prove this. In the meantime...
Exo 28:1 And take thou unto thee Aaron thy brother, and his sons with him, from among the children of Israel, that he may minister unto me in the priest's office, even Aaron, Nadab and Abihu, Eleazar and Ithamar, Aaron's sons.
Exo 28:2 And thou shalt make holy garments for Aaron thy brother for glory and for beauty.
Exo 28:3 And thou shalt speak unto all that are wise hearted, whom I have filled with the spirit of wisdom, that they may make Aaron's garments to consecrate him, that he may minister unto me in the priest's office.
Teh Aaronic Piresthood was NOT established until months after The Ten Commandments were given to the people. Were teh Ten Commandments around prior to Ex 20?
Exo 16:28 And the LORD said unto Moses, How long refuse ye to keep my commandments and my laws?
The word for Laws here is...
H8451
תּרה תּורה
tôrâh tôrâh
to-raw', to-raw'
From H3384; a precept or statute, especially the Decalogue or Pentateuch: - law.
Well now, that is a problem for your theory. Let's look back further in time...
Gen 26:5 Because that Abraham obeyed my voice, and kept my charge, my commandments, my statutes, and my laws.
The word here for Laws is...
H8451
תּרה תּורה
tôrâh tôrâh
to-raw', to-raw'
From H3384; a precept or statute, especially the Decalogue or Pentateuch: - law.
And this was several hundred years before Aaron was a twinkle in Amram's eye.
Now what does Paul say?
Rom 5:12 Wherefore, as by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned:
Who was the "one man"? Do you disagree with this being Adam? (that would be another discussion)
Rom 5:13 (For until the law sin was in the world: but sin is not imputed when there is no law.
What does "until the Law" mean? The time span up until Mt. Sinai.
Paul plainly tells us that without Law there is no transgression...
Rom 4:15 Because the law worketh wrath: for where no law is, there is no transgression.
Something early on I did was to find a case or statement of every one of the Ten Commandments prior to Ex 20:1. They are all there and if full force.
2) Furthermore, "a better hope is introduced (which did make perfect), by which we draw near to God." (Heb 7:19)
That "better hope" (which did make perfect) is the new covenant (Lk 22:20), which assures us of complete redemption (Heb 10:4) and brings us into the presence of God.
Nice stretch, but not correct. If you simply read the chapter you see that...
Heb 10:1 For the law having a shadow of good things to come, and not the very image of the things, can never with those sacrifices which they offered year by year continually make the comers thereunto perfect.
Heb 10:2 For then would they not have ceased to be offered? because that the worshippers once purged should have had no more conscience of sins.
Heb 10:3 But in those sacrifices there is a remembrance again made of sins every year.
Heb 10:4 For it is not possible that the blood of bulls and of goats should take away sins.
Heb 10:12 But this man, after he had offered one sacrifice for sins for ever, sat down on the right hand of God;
Heb 10:16 This is the covenant that I will make with them after those days, saith the Lord, I will put my laws into their hearts, and in their minds will I write them;
The New Covenant is the writing of the Torah (look at Jer 31:33 and see what the inspired word for Law is) in our hearts and minds.
Heb 10:17 And their sins and iniquities will I remember no more.
Heb 10:18 Now where remission of these is, there is no more offering for sin.
Heb 10:19 Having therefore, brethren, boldness to enter into the holiest by the blood of Jesus,
Heb 10:20
By a new and living way, which he hath consecrated for us, through the veil, that is to say, his flesh;
This new and living way is the forgiveness of sin by the offering a perfect sacrifice HIS FLESH.
3) The Old (Sinaitic) Covenant was made obsolete (Heb 8:13), not by changing the law for the priesthood, but by changing and setting aside the Mosaic law.
Well if that is the case then the Priesthood didn't change? It was only the Law that changed? No, when we read the whole chapter, we see the subject is the changing of the Priesthood from the Aaronic Priesthood, that had to offer animal sacrifices continually, to the Melchisidec Priesthood with one offering once for all...
Heb 10:12 But this man, after he had offered one sacrifice for sins for ever, sat down on the right hand of God;
Heb 10:13 From henceforth expecting till his enemies be made his footstool.
Heb 10:14 For by one offering he hath perfected for ever them that are sanctified.
Heb 7:12 does not refer to a change of the Aaronic priesthood law,
but to a change and setting aside of the Mosaic Law (Heb 7:18-19).
Oddly enough your entire statement is incorrect. Not only is it about a change in the Priesthood ("For the priesthood being changed," whatever could that mean?) the Law concerning the Priesthood was not set aside, it was changed. There is a difference between changing something and setting it aside. Ever change the color of a room? Did that set it aside? Ever change your hair style? Bald now are you?
What do the verses around Hebrews 7:12 say?
Heb 7:11 If therefore
perfection were by the Levitical priesthood, (for under it the people received the law,) what further need was there that another
priest should rise after the order of Melchisedec, and
not be called after the order of Aaron?
Heb 7:12 For the priesthood being changed, there is made of necessity a change also of the law.
Heb 7:13 For he of whom these things are spoken pertaineth to
another tribe, of which
no man gave attendance at the altar.
Heb 7:14 For it is evident that our Lord sprang out of Juda;
of which tribe Moses spake nothing concerning priesthood.
Heb 7:15 And it is yet far more evident:
for that after the similitude of Melchisedec there ariseth another priest,
Heb 7:16 Who is made, not after the law of a carnal commandment, but after the power of an endless life.
Heb 7:17 For he testifieth, Thou art a
priest for ever after the order of Melchisedec.
The author (I believe to be Paul) is plainly speaking of the Priesthood, not the setting aside of the Law.