“For he finds fault with them when he says: ‘Behold, the days are coming, declares the Lord, when I will establish a new covenant with the house of Israel and with the house of Judah'” (Hebrews 8:8 ESV).
As mentioned earlier, a covenant differs from other types of agreements in one important respect: the terms of a covenant are non-negotiable. In the case of a Biblical covenant, God always initiates the terms, just as we see here: “I will establish a new covenant…”
This covenant does not represent an updated or modified version of an earlier agreement. Instead, the word used to describe this covenantal arrangement denotes “…that which is unaccustomed or unused, not ‘new’ in time, [or] recent, but ‘new’ as to form or quality, of different nature from what is contrasted as old.” (1)
We should also note that this covenant was established with “the house of Israel and the house of Judah.” This represents a poetic designation for the twelve sons of Jacob, the Old Testament patriarch, and their descendants (or “tribes”). Sometime around 922 BC, two of those tribes (Judah and Benjamin) broke away from the descendants of the other ten sons to form the house of Judah.
Nevertheless, God made certain to ensure that no one was excluded from this New Covenant- including those of non-Jewish heritage…
“You Gentiles by birth… remember what you were in the past. At that time you were apart from Christ. You were foreigners and did not belong to God’s chosen people. You had no part in the covenants, which were based on God’s promises to his people, and you lived in this world without hope and without God.
But now, in union with Christ Jesus you, who used to be far away, have been brought near by the blood of Christ… It is through Christ that all of us, Jews and Gentiles, are able to come in the one Spirit into the presence of the Father” (Ephesians 2:11-13, 18 GNT).
The following commentary explains the extent of this covenantal relationship…
“Though the New Covenant is specifically focused on Israel (cf. house of Israel and ‘house of Judah’ in Jer_31:31), it is clear that Christians of the present time also stand under its blessings (cf. Luk_22:20; 1Co_11:25; 2Co_3:6). This perception does not lead to an inappropriate confusion between Israel and the church. The New Covenant is God’s appointed vehicle for fulfilling the Abrahamic blessings to Israel. But the Abrahamic Covenant also promised universal blessing, so the New Covenant becomes as well God’s vehicle of salvation for believers since the Cross.” (2)
(1) G2537 kainos Vine’s Expository Dictionary of Biblical Words © 1985, Thomas Nelson Publishers https://www.blueletterbible.org/search/dictionary/viewtopic.cfm?topic=VT0001914
(2) William Macdonald, Believer’s Bible Commentary Edited by Arthur Farstad Thomas Nelson Publishers p.800