Paul tells us about the two covenants in Galatians 3
Both saved Christians and saved Jews are one new man in Christ (Ephesians 2:14-18) and are of the covenant with the new Jerusalem from above which is free.
You do know the sons are free of this world having their citizenship in heaven, so why would there be an old earthly millennial reign? Makes no sense to me and it's a really carnal doctrine of the flesh.
Since God foreknew His people, guess what He saves them, none He foreknew are cast away, but all the others God did not foreknow are never saved. Like Christ tells them, I never knew you, depart from me you workers of evil. Evil?? Yes, as their father is the devil who planted them in God's field the world. Refer the parables of the TARES. Only the elect of God obtain salvation as God is their Father, and he gave them new birth. At some point if anyone turns to the Lord, then you can know they are elect if they hold firm their confidence in God to the end (from our POV, God already knows His people who will believe until the end as God elected them). Election in the NC means chosen by God for salvation, so all who are elected by God are saved.
Hebrews 3
5 And Moses indeed
was faithful in all His house as a servant, for a testimony of those things which would be spoken
afterward,
6
but Christ as a Son over His own house, whose house we are if we hold fast the confidence and the rejoicing of the hope [a]firm to the end.
Romans 11
I say then, has God cast away His people? Certainly not! For I also am an Israelite, of the seed of Abraham,
of the tribe of Benjamin. 2 God has not cast away His people whom He foreknew. Or do you not know what the Scripture says of Elijah, how he pleads with God against Israel, saying, 3 “Lord, they have killed Your prophets and torn down Your altars, and I alone am left, and they seek my life”? 4 But what does the divine response say to him? “I have reserved for Myself seven thousand men who have not bowed the knee to Baal.” 5 Even so then, at this present time there is a remnant according to the election of grace. 6 And if by grace, then
it is no longer of works; otherwise grace is no longer grace. [
a]But if
it is of works, it is no longer grace; otherwise work is no longer work.
7 What then? Israel has not obtained what it seeks; but the elect have obtained it, and the rest were blinded. 8 Just as it is written:
“God has given them a spirit of stupor,
Eyes that they should not see
And ears that they should not hear,
To this very day.”
You can NOT educate someone to know the Lord and be saved. Only God teaches His elect. Read Hebrews 8 on the New Covenant.
Galatians 3
26 For you are all sons of God through faith in Christ Jesus. 27 For as many of you as were baptized into Christ have put on Christ. 28 There is neither Jew nor Greek, there is neither slave nor free, there is neither male nor female; for you are all one in Christ Jesus.
29 And if you are Christ’s, then you are Abraham’s seed, and heirs according to the promise.
Galatians 4
Two Covenants
21 Tell me, you who desire to be under the law, do you not hear the law? 22 For it is written that Abraham had two sons: the one by a bondwoman, the other by a freewoman. 23 But he
who was of the bondwoman was born according to the flesh, and he of the freewoman through promise, 24 which things are symbolic. For these are [
g]the two covenants: the one from Mount Sinai which gives birth to bondage, which is Hagar— 25 for this Hagar is Mount Sinai in Arabia, and corresponds to Jerusalem which now is, and is in bondage with her children— 26 but the Jerusalem above is free, which is the mother of us all. 27 For it is written:
“Rejoice, O barren,
You who do not bear!
Break forth and shout,
You who are not in labor!
For the desolate has many more children
Than she who has a husband.”
28 Now we, brethren, as Isaac
was, are children of promise. 29 But, as he who was born according to the flesh then persecuted him
who was born according to the Spirit, even so
it is now. 30 Nevertheless what does the Scripture say? “Cast out the bondwoman and her son, for the son of the bondwoman shall not be heir with the son of the freewoman.” 31 So then, brethren, we are not children of the bondwoman but of the free.