But it is instructive to consider the terms of the new covenant as here cited from the prophet, though from the Septuagint rather than the Hebrew, and not without change even from that.
“For this [is] the covenant which I will make with the house of Israel after those days, saith the Lord; giving my laws into their mind, I will also write them upon their hearts; and I will be to them for God, and they shall be to me for people. And they shall not teach each his [fellow] citizen and each his brother, crying, Know the Lord, because all shall know me from little one unto great of them” (Heb. 8:10-11).
The essence of the new covenant is that Jehovah undertakes its accomplishment. The first covenant could not but fail, because it depended, not on God, but on the Israelite; and the Israelite was already a sinful man. This the law made evident. As long as men only hear, and speak, and judge others (perhaps satisfactorily to themselves), they may keep up a claim of their own righteousness. It is quite another thing when they strive seriously to obey. Then they find out that they are without strength, enemies of God, and ungodly. Christ comes from God to meet the need, giving them life on the faith of Himself, and dying for their sins that they may be remitted of God.
But while there was evident propriety, in writing to Hebrew confessors, to quote from the inspired words of Jeremiah, it is an error to assume that the gospel as preached now is the fulfillment of the prediction. It is perfectly legitimate to apply the words to privileges conferred by the gospel without denying that the prophet has in view the days when the house of Israel and the house of Judah shall alike be blessed under the reign of the Messiah; whereas during gospel times the Gentile is as open to the call of grace as the Jew, the cross having proved that all sinned and come short of the glory of God. There is now no difference any more in them than in indiscriminate grace. Salvation is preached to both alike.
But in the days which strictly the prophecy contemplates, God will own His ancient people again and never more shall the seed of Israel cease from being a nation before Jehovah forever. In those days shall the city be built to Jehovah from the tower of Hananeel unto the gate of the corner. And the measuring line shall yet go forth over against it upon the hill Gareb, and shall compass about to Goah. And the whole valley of the dead bodies, and of the ashes, and all the fields unto the brook of Kidron, unto the corner of the horse-gate toward the east, shall be holy unto Jehovah; it shall not be plucked up, nor thrown down, any more forever. It is the restoration of the people and the land and the city, when Messiah reigns on His own throne; of which the reader can find more in Isa. 11; 12; 35; 65; 66; Jeremiah 16-18; 30; 32: 37-44; 33; Ezek. 40-48, and in the minor prophets, especially Zech. 12-14.
Application of part to gospel times is not denied; for grace now reigns through righteousness by Jesus Christ our Lord, as then a King shall reign in righteousness. But judgment shall return to righteousness at that epoch, and the inhabitants of the world will learn righteousness so as they never do now. All the earth shall be filled with the glory of Jehovah in that day, which it never will in this day. To the believer now the principle of the new covenant applies, as far as his soul is concerned; but Israel will enjoy its terms directly and unqualifiedly, when the Branch of righteousness, grown to David, shall execute judgment and righteousness in the land, and all nations are blessed in Him.
The first blessing here specified is that the Lord not only gives His laws into the mind, but also writes them upon the heart. It is in pointed contrast with the first covenant written on stones. The law as a system was external, and was characterized by an elaborate ritualism, visible and palpable, when anointed priest, Levite, ruler, and ordinary Israelite had his defined place, with meats and drinks, and divers washings, and carnal ordinances, as well as specific gifts and sacrifices which could not make him that did the service perfect as pertaining to the conscience. The blood of bulls and goats, and the ashes of a heifer sprinkling the unclean, could not do more than sanctify to the purifying of the flesh. The laws were outside the Israelite; they were not written on his heart. Far different is the work of grace now. God gives them into the mind and writes them on the heart of every believer. There is for the Christian a renewing of the mind, and the love of God shed abroad in the heart by the Holy Spirit given to him. The principle of the new covenant is not only verified, but in a richer way spiritually than Israel can have by-and-by, whatever their wondrous privileges in the exclusion of Satan and the presence of Christ, and the whole creation delivered from the bondage of corruption into the liberty of the glory of the children of God then reigning with Him.
Next, “I will be to them for God, and they shall be to Me for people.” As this will be Israel's portion in that day, so it is ours now. It is not less ours, because we can say by the Spirit “Abba, Father,” Christ's Father and our Father, Christ's God and our God. As before, it will be no longer an imposed ordinance or a possibly vain title of relationship. All is by His grace made real, intrinsic, and abiding. All the blessing that is involved in what God is to His people is secured, as His people are secured in their due place toward Him. But we can add our Father, though this did not fall within the design of the epistle to unfold as we find it elsewhere.
Further, “And they shall not teach each his [fellow] citizen, and each his brother, saying, Know the Lord, because all shall know Me from little one unto great of them.” This is another privilege in which we more than anticipate the blessings of Jehovah's manifested kingdom. The Son of God is come and has given us an understanding that we may know Him that is true. And no wonder; for the Christian has eternal life in the Son, as he has also the Holy Spirit dwelling in him, both capacity and power, that we might know the things that are freely given to us of God. So it will be when the new covenant is established with both the houses of Israel. “In that day shall the deaf hear the words of the book, and the eyes of the blind shall see out of obscurity and out of darkness. They also that erred in spirit shall come to understanding, and they that murmured shall learn doctrine.” As it is elsewhere written, which also explains it, “All thy children shall be taught of Jehovah; and great shall be the peace of thy children.” Hence it will be no question of teaching, each his fellow-citizen, and each his brother. The salvation which Israel enjoys in that day so illustrates the scripture, that there will be no need of objective knowledge (γνῶσις) for the ignorant, because all shall have intrinsically possessed conscious knowledge (ἐιδήσουσι) from little even to great of them. The universality of the result testifies that God it is Who ensures it; for under human teaching, however good, we see every degree of proficiency and at best knowledge far from perfect. Compare also Joel 2:28. The outpoured Spirit gives understanding and power.
Here too in Christianity we may observe remarkable analogy. It is in addressing the babes (παιδία) of God's family that the apostle John declares “ye have an unction from the Holy One, and ye know all things. I have not written unto you, because ye know not the truth, but because ye know it, and that no lie is of the truth.” This is of course true of the “fathers” and “young men” in Christ; but it is said expressly to those who most needed such encouragement, exposed as they were to seducers who boasted of their knowledge and undermined Christ. “But the anointing which ye have received of Him abideth in you, and ye need not that any man teach you but as the same anointing teacheth you of all things, and is truth, and is no lie, and even as it hath taught you, ye shall abide in Him” (1 John 2:20-21, 27). Teachers there are, and those that rule or guide, while Christ is on the throne of God; but they should be the first to maintain the privileges of the simplest believer.