The mystery of Christ.
That's a terribly far stretch. Paul is the only one that ever uses the analogy of a BODY for believers. That is because God had long ago given the gentiles up to the own sinful lusts and He separated a people of Himself on the earth: Israel.
Then you're not a good reader.
Isa 60:15-16 (AKJV/PCE)
(60:15) Whereas thou hast been forsaken and hated, so that no man went through [thee], I will make thee an eternal excellency, a joy of many generations. (60:16) Thou shalt also suck the milk of the Gentiles, and shalt suck the breast of kings: and thou shalt know that I the LORD [am] thy Saviour and thy Redeemer, the mighty One of Jacob.
Do you think that ^THAT^ refers to Christ?
You cannot see the parallels with Rev 21?
Rev 21:22-26 (AKJV/PCE)
(21:22) And I saw no temple therein: for the Lord God Almighty and the Lamb are the temple of it. (21:23) And the city had no need of the sun, neither of the moon, to shine in it: for the glory of God did lighten it, and the Lamb [is] the light thereof. (21:24) And the nations of them which are saved shall walk in the light of it: and the kings of the earth do bring their glory and honour into it. (21:25) And the gates of it shall not be shut at all by day: for there shall be no night there. (21:26) And they shall bring the glory and honour of the nations into it.
Isa 60:19-21 (AKJV/PCE)
(60:19) The sun shall be no more thy light by day; neither for brightness shall the moon give light unto thee: but the LORD shall be unto thee an everlasting light, and thy God thy glory. (60:20) Thy sun shall no more go down; neither shall thy moon withdraw itself: for the LORD shall be thine everlasting light, and the days of thy mourning shall be ended. (60:21) Thy people also [shall be] all righteous: they shall inherit the land for ever, the branch of my planting, the work of my hands, that I may be glorified.
Your blinders are still on.
Hebrews is ALL about the HEBREWS, as is Revelation.
Note that "receiving a kingdom" is NOT the same as RECEIVED a kingdom. The kingdom HAS NOT yet come.
The NEW COVENANT is between GOD and ISRAEL.... that is what the Bible says.
Heb 8:6-13 (AKJV/PCE)
(8:6) But now hath he obtained a more excellent ministry, by how much also he is the mediator of a better covenant, which was established upon better promises. (8:7) For if that first [covenant] had been faultless, then should no place have been sought for the second. (8:8) For finding fault with them, he saith, Behold, the days come, saith the Lord, when I will make a new covenant with the house of Israel and with the house of Judah: (8:9) Not according to the covenant that I made with their fathers in the day when I took them by the hand to lead them out of the land of Egypt; because they continued not in my covenant, and I regarded them not, saith the Lord. (8:10) For this [is] the covenant that I will make with the house of Israel after those days, saith the Lord; I will put my laws into their mind, and write them in their hearts: and I will be to them a God, and they shall be to me a people: (8:11) And they shall not teach every man his neighbour, and every man his brother, saying, Know the Lord: for all shall know me, from the least to the greatest. (8:12) For I will be merciful to their unrighteousness, and their sins and their iniquities will I remember no more. (8:13) In that he saith, A new [covenant], he hath made the first old. Now that which decayeth and waxeth old [is] ready to vanish away.
This confirmed EXACTLY what was said in Jeremiah 31:
Jer 31:31-34 (AKJV/PCE)
(31:31) ¶ Behold, the days come, saith the LORD, that I will make a new covenant with the house of Israel, and with the house of Judah: (31:32) Not according to the covenant that I made with their fathers in the day [that] I took them by the hand to bring them out of the land of Egypt; which my covenant they brake, although I was an husband unto them, saith the LORD: (31:33) But this [shall be] the covenant that I will make with the house of Israel; After those days, saith the LORD, I will put my law in their inward parts, and write it in their hearts; and will be their God, and they shall be my people. (31:34) And they shall teach no more every man his neighbour, and every man his brother, saying, Know the LORD: for they shall all know me, from the least of them unto the greatest of them, saith the LORD: for I will forgive their iniquity, and I will remember their sin no more.
Why is this so difficult for you to understand? Believe it.