I think you completely misunderstand the context and contrast in these verses.
The entire old covenant is contrasted with the new covenant.
The entire old covenant is contrasted with the new covenant.
In the context of the letter addressing Hebrews, who were considering compromising their faith by returning to Judaism and the old covenant in order to gain relief from persecution by their family and friends, the writer warns them that to trade their spiritual birthright for temporary ease in this world as did Esau (12:16), would deprive them of Christ's blessing (12:17).
That is the context in which he presents the contrast between the Sinaitic (Old) Covenant
and the New Covenant.
18For you have not come to [a mountain] that can be touched and to a blazing fire, and to darkness and gloom and whirlwind, 19and to the blast of a trumpet and the sound of words which [sound was such that] those who heard begged that no further word be spoken to them. 20For they could not bear the command, "IF EVEN A BEAST TOUCHES THE MOUNTAIN, IT WILL BE STONED." 21And so terrible was the sight, [that] Moses said, "I AM FULL OF FEAR and trembling."
The entire description above contrasts the OT, Moses, Sinai, Law. What follows is a clear description of the new, the Church.
22But you have come to Mount Zion and to the city of the living God, the heavenly Jerusalem, and to myriads of angels, 23to the general assembly and church of the firstborn who are enrolled in heaven, and to God, the Judge of all, and to the spirits of [the] righteous made perfect, 24and to Jesus, the mediator of a new covenant, and to the sprinkled blood, which speaks better than [the blood] of Abel.
The general assembly and church of the firstborn ones are the saints the Hebrews knew that had already died since the Church had been founded at Pentecost. The idea that the entirety of OT saints are somehow the firstborn ones does not do justice to the context, the clear contrast from v. 22 "But you have come", and the sense of the text and the meaning of the word firstborn.
The OT saints can in no way be firstborn ones because they were before Christ! Isn't this clear from the text?
The firstborn are the ones who first believe in Christ, the mediator of the new covenant.
The entire description above contrasts the OT, Moses, Sinai, Law. What follows is a clear description of the new, the Church.
22But you have come to Mount Zion and to the city of the living God, the heavenly Jerusalem, and to myriads of angels, 23to the general assembly and church of the firstborn who are enrolled in heaven, and to God, the Judge of all, and to the spirits of [the] righteous made perfect, 24and to Jesus, the mediator of a new covenant, and to the sprinkled blood, which speaks better than [the blood] of Abel.
The general assembly and church of the firstborn ones are the saints the Hebrews knew that had already died since the Church had been founded at Pentecost. The idea that the entirety of OT saints are somehow the firstborn ones does not do justice to the context, the clear contrast from v. 22 "But you have come", and the sense of the text and the meaning of the word firstborn.
The OT saints can in no way be firstborn ones because they were before Christ! Isn't this clear from the text?
The firstborn are the ones who first believe in Christ, the mediator of the new covenant.
"church of the firstborn."
(Too much focus on OT prophecy, and not enough on the typology of the NT gospel?)
"Every firstborn male is to be consecrated to the Lord." (Lk 2:23)
God bought back (redeemed) from the destroying angel all the firstborn of Israel,
both men and animals in the tenth plague (Ex 12:21-29).
Because God purchased them from death, they were his by right of purchase
(Ex13:1, 12-15, 22:29).
Therefore, the firstborn animals were consecrated (given over to God) by sacrifice
(Ex 13:15),
unless it was an unclean animal which was either redeemed (bought back) or destroyed
(Ex 13:13, 34:20).
And the firstborn sons were consecrated to God for full-time service to him (Ex 13:2).
God then substituted the Levites and their livestock for consecration to his full-time service
in place of the firstborn sons of Israel and their first-born animals (Nu 3:9-13, 41, 44-51,
8:15-19),
and then gave to the Levites his right to ownership of all firstborn males, both men and
animals (Nu 18:14-15).
Therefore, all the firstborn sons of Israel had to be bought back (redeemed) from the Levites
for five shekels of silver (Ex 13:13, 15, 30:12, 3:20; Nu 18;15-16).
Excellent typology of the gospel. . .
1) In the NT, the "church of the firstborn" (Heb 12:23) are all the redeemed,
So yes, all the OT saints are also the redeemed firstborn in the NT,
who also have been delivered from the destroying angel (Satan - 1Pe 5:8; Jn 10:10)
and bought back (redeemed) from eternal death (Eph 2:1, 5; Col 2:13),
by Christ our priest, who was substituted for us (Mt 20:28),
to whom God has exclusive right by purchase (1Co 6:20, 7:23; Ac 20:28b; 1Pe 2:9;
Rev 5:9, 14:4),
and are, therefore, to be consecrated to the Lord (Ro 6:13; 2Co 5:15).
. . .which gospel also includes
the destruction of all the unclean (unbelievers) who are not redeemed/consecrated
(Jn 3:18, 36; Heb 12:14) as in Ex 13:13, 34:20.
2) The "righteous men made perfect" (completed, sins remitted--Heb 10:4,
not just covered--Ro 4:7) are all the redeemed who are in their graves,
including the OT saints whose sins were only covered (Heb 10:4)
until they were remitted by the cross (Ro 3:25).
3) The Church is the Bride (Eph 5:31-32; 2Co 11:2; Rev 21:2, 9), the New Jerusalem,
the heavenly Jerusalem (Gal 4:25; Rev 3:12, 21:10),
which includes the OT saints (Rev 21:9-12; cf Eze 48:3-34).
Scripture is clear that the OT saints are also in the church of the firstborn (Heb 12:23).