This study follows a biblical-theological thread from Psalm 40 to Jeremiah 31 and then to Jesus’ institution of the New Covenant. Psalm 40 presents God’s instruction internalized in the heart; Jeremiah 31 develops that theme as the promise of a New Covenant; and the New Testament identifies that covenant as inaugurated through Christ’s once-for-all sacrifice.
The goal is to see both the original Old Testament contexts and the way the New Testament brings those promises to fulfillment in Christ.
Study Overview
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Psalm 40 presents a servant who delights to do God’s will because God’s instruction is internalized within him.
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Jeremiah 31 promises a New Covenant in which God writes His law on the hearts of His people.
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Jesus identifies the New Covenant with His blood, and Hebrews presents His sacrifice as the definitive fulfillment of that promise.
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The New Testament also explains how Gentile believers come to share in the covenant’s blessings through union with Christ.
1. Psalm 40: God’s Instruction Within the Heart
6 In sacrifice and offering you have not delighted, but you have given me an open ear. Burnt offering and sin offering you have not required.
7 Then I said, “Behold, I have come; in the scroll of the book it is written of me:
8 I delight to do your will, O my God; your law is within my heart.”
Key Observation
In Psalm 40:8, the Hebrew word translated “law” is תּוֹרָה — torah.
It means more broadly “instruction,” “teaching,” or “direction”—not merely “law” in the modern legal sense.
This means the line can be read not only as “Your law is within my heart,” but also as “Your instruction is within my heart.”
The phrase in Hebrew is וְתוֹרָתְךָ בְּתוֹךְ מֵעָי — ve-toratekha betokh me‘ai, literally something like “and your Torah is within my inward parts.”
That last phrase is stronger than merely “I know God’s rules.” David is saying God’s revealed instruction has become internalized—deep within him—and he delights to do God’s will.
That fits beautifully with Jeremiah 31:33, where God promises, “I will put my law within them, and I will write it on their hearts.”
Study Takeaway
Psalm 40 anticipates the internal, heart-level obedience that becomes central to Jeremiah’s promise of the New Covenant.
2. Jeremiah 31: The Promise of the New Covenant
31 “Behold, the days are coming, declares the Lord, when I will make a new covenant with the house of Israel and the house of Judah, 32 not like the covenant that I made with their fathers on the day when I took them by the hand to bring them out of the land of Egypt, my covenant that they broke, though I was their husband, declares the Lord. 33 For this is the covenant that I will make with the house of Israel after those days, declares the Lord: I will put my law within them, and I will write it on their hearts. And I will be their God, and they shall be my people. 34 And no longer shall each one teach his neighbor and each his brother, saying, ‘Know the Lord,’ for they shall all know me, from the least of them to the greatest, declares the Lord. For I will forgive their iniquity, and I will remember their sin no more.”
35 Thus says the Lord, who gives the sun for light by day and the fixed order of the moon and the stars for light by night, who stirs up the sea so that its waves roar— the Lord of hosts is his name: 36 “If this fixed order departs from before me, declares the Lord, then shall the offspring of Israel cease from being a nation before me forever.”
37 Thus says the Lord: “If the heavens above can be measured, and the foundations of the earth below can be explored, then I will cast off all the offspring of Israel for all that they have done, declares the Lord.”
38 “Behold, the days are coming, declares the Lord, when the city shall be rebuilt for the Lord from the Tower of Hananel to the Corner Gate. 39 And the measuring line shall go out farther, straight to the hill Gareb, and shall then turn to Goah. 40 The whole valley of the dead bodies and the ashes, and all the fields as far as the brook Kidron, to the corner of the Horse Gate toward the east, shall be sacred to the Lord. It shall not be plucked up or overthrown anymore forever.”
Who Is Addressed in Jeremiah 31?
In Jeremiah 31:33, “them” refers to “the house of Israel and the house of Judah” from verse 31.
The flow of the passage is straightforward:
“Behold, the days are coming, declares the LORD, when I will make a new covenant with the house of Israel and the house of Judah…” — Jeremiah 31:31, ESV
Then verse 33 says:
“For this is the covenant that I will make with the house of Israel after those days, declares the LORD: I will put my law within them, and I will write it on their hearts.”
So, in the original historical context, “them” is covenant Israel—specifically the people identified as Israel and Judah.
At the same time, the New Testament develops this promise further. Hebrews 8:8–12 quotes Jeremiah 31:31–34 and presents the New Covenant as inaugurated through Jesus, the mediator of a better covenant.
A helpful distinction is:
Explicitly in Jeremiah: “them” = Israel and Judah.
In the New Testament fulfillment: those who belong to the new covenant through Christ receive this heart-writing work of God.
That distinction matters because Jeremiah speaks from within Israel’s covenant history, while the New Testament explains how that promise is fulfilled in Christ and shared with all who belong to Him. The question is not whether Gentile believers receive New Covenant blessings, but how Scripture explains their inclusion.
Study Takeaway
Jeremiah’s original audience is Israel and Judah, but the New Testament shows that the promised covenant reaches its fulfillment in Christ and is shared by all who belong to Him.
This raises a second question: if Jeremiah is promising a New Covenant, when does that covenant begin?
Question: When Is the New Covenant Established?
In Jeremiah 31, is the New Covenant being established at the moment Jeremiah proclaims it, or is Jeremiah prophesying a future covenant that will ultimately be inaugurated through Jesus?
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Is Jeremiah announcing the covenant as already active in his own historical context?
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Or is he looking ahead prophetically to the New Covenant Jesus later identifies with His blood?
Short Answer
Jeremiah is prophesying a future covenant. He is not saying the New Covenant was formally established when he delivered the prophecy.
Key Text
“Behold, the days are coming, declares the LORD, when I will make a new covenant…” — Jeremiah 31:31, ESV
In Jeremiah’s historical setting, then, God is promising something still to come.
New Testament Fulfillment
The New Testament explicitly identifies Jeremiah’s promised covenant with Jesus. At the Last Supper, Jesus says:
“This cup that is poured out for you is the new covenant in my blood.” — Luke 22:20, ESV
Paul repeats this language in 1 Corinthians 11:25, and Hebrews 8 quotes Jeremiah 31:31–34 at length while presenting Jesus as the mediator of a better covenant.
Study Summary
Jeremiah announces the New Covenant; Jesus inaugurates it.
One important nuance remains: Jeremiah himself may not have understood every detail of how the prophecy would be fulfilled in Jesus. But from the standpoint of the completed New Testament witness, the connection is explicit: the New Covenant Jeremiah foretold is established through Christ’s sacrificial death.
Distinctive Features
“not like the covenant that I made with their fathers…” — Jeremiah 31:32
Jeremiah contrasts the New Covenant with the former covenant made with Israel’s fathers. Its defining features are internal transformation, restored relationship with God, and definitive forgiveness of sins.
That is why Hebrews treats Jeremiah 31 as a major prophecy of Christ and the gospel.
Question: Does Jeremiah 31 Include Gentiles?
Because Jeremiah names “Israel and Judah,” not “Israel, Judah, and the Gentiles,” the question becomes more precise: does Jeremiah 31 itself include Gentiles, or does their inclusion emerge later through the New Testament’s explanation of union with Christ?
Short Answer
Yes. This observation is important. In Jeremiah 31 itself, the New Covenant promise is explicitly addressed to Israel and Judah, not to “all humanity” in general or to Gentiles by name.
Original Context
Jeremiah’s wording is explicit:
“Behold, the days are coming, declares the LORD, when I will make a new covenant with the house of Israel and the house of Judah.” — Jeremiah 31:31, ESV
And verse 33 narrows the wording again:
“For this is the covenant that I will make with the house of Israel after those days…”
So exegetically, we should not insert Gentiles into Jeremiah 31:31–34. They aren’t mentioned there.
New Testament Development
The answer develops later in Scripture, especially in Paul’s teaching about Gentiles being brought near through Christ.
“alienated from the commonwealth of Israel and strangers to the covenants of promise, having no hope and without God in the world.” — Ephesians 2:12, ESV
Notice that. Paul doesn’t say, “Those covenants were originally made with you Gentiles too.” Quite the opposite. Gentiles were outsiders.
“But now in Christ Jesus you who once were far off have been brought near by the blood of Christ.” — Ephesians 2:13, ESV
Two Truths to Hold Together
- Jeremiah’s New Covenant is promised to Israel and Judah.
That is simply what the text says. We should not erase it.
- Gentiles are brought into the blessings of that covenant through Christ.
Paul uses several striking images for this.
In Romans 11, Gentile believers are wild olive branches grafted into an existing cultivated olive tree:
“you, although a wild olive shoot, were grafted in among the others and now share in the nourishing root of the olive tree” — Romans 11:17, ESV
Notice again what Paul doesn’t say. God doesn’t plant a completely separate Gentile tree. Gentiles are grafted into something already existing.
Similarly, in Galatians:
“And if you are Christ’s, then you are Abraham’s offspring, heirs according to promise.” — Galatians 3:29, ESV
And Ephesians says Jew and Gentile become:
“one new man” — Ephesians 2:15, ESV
and Gentile Christians are:
“fellow citizens with the saints and members of the household of God.” — Ephesians 2:19, ESV
Clarifying the Claim
It is worth sharpening the earlier formulation.
Saying simply that “Jeremiah’s promise applies to Christians” is true at the level of New Testament fulfillment, but it can obscure Jeremiah’s original wording.
A more precise formulation is:
God promised the New Covenant to Israel and Judah. Jesus established that promised New Covenant through His blood, and through union with Christ Gentile believers are brought into its blessings alongside believing Jews.
That is substantially different from saying:
“Jeremiah was actually talking about Gentiles too.”
He wasn’t—not explicitly.
Biblical-Theological Summary
Instead, Paul gives a richer picture:
Promises given within Israel’s covenant history → fulfilled in Israel’s Messiah → Gentiles brought into those promises through faith in that Messiah → Jew and Gentile becoming one people in Christ.
That’s why Ephesians 2, Galatians 3, and Romans 11 really need to be read alongside Jeremiah 31.
The conclusion can now bring these strands together: Jeremiah names Israel and Judah as the immediate covenant recipients, while the New Testament shows that Christ fulfills the promise and brings Gentiles into its blessings through union with Him.
Final Takeaway
One more Old Testament thread sharpens the conclusion: Jeremiah is not the only prophet describing this coming era. Other prophets, especially Isaiah, explicitly speak of the nations being brought into God’s salvation.
Jeremiah emphasizes Israel and Judah restored under the New Covenant, while Isaiah supplies the complementary horizon: the nations are brought to Israel’s Messiah, and God’s salvation reaches the ends of the earth.
That is the pattern Acts unfolds: the gospel goes first to Israel, then outward to the nations, as the witness to Christ extends the promised salvation to the ends of the earth.