Jesus kept the old covenant perfectly even while exemplifying and teaching his disciples how to live out the new covenant. However, when he died, he inaugurated the new covenant with his blood. Not only did his sacrifice atone for sins committed under the old system, but it also brought it to an end.
Jesus kept the old covenant perfectly (Gal 4.4; Mt 5.17-18). He also taught how to live the new covenant while exemplifying the new covenant lifestyle. Thus, he did both at the same time. He lived during the overlap: when the old covenant was still in effect and while he was already pioneering how to live out the new covenant.
If Jesus kept both the old covenant and the new covenant then we should too, right? Shouldn’t we follow Jesus’ example in keeping the Law or should we just obey his new covenant teachings? To answer this, we must consider the earthshattering results of Christ’s work on the cross to see how it affected the old and new covenants.
Even before the crucifixion, Jesus prepared his disciples for the new covenant by intertwining it in the memorial meal we know as communion (Luke 22.19-20; 1 Cor 11.25).
New Covenant Theology in Hebrews
The densest and best explanation for how Jesus’ death, resurrection, and ascension affect the covenants is the book of Hebrews. Here is a brief outline of some of the key points made in this epistle as they relate to the old and new covenants:
The New Covenant Is Better Than the Old
- (ch 1-2) since Jesus is God’s son, he is better than the angels who mediated the old covenant
- (ch 3) Moses was a faithful servant but Jesus is better—a faithful son
- (ch 7) Jesus’ priesthood is better than Aaron’s because it’s after Melchizedek’s order
- (ch 8) Jesus’ covenant (new covenant) is better than the old b/c it has better promises
- (ch 9) Jesus’ heavenly priestly service is better than the earthly Levites b/c he transforms us and directly accesses the true holy place
- (ch 10) Jesus’ sacrifice is better b/c it takes away sin (not just covering it)
The best way to understand how this all works is to delve into chapters 7-10.
Hebrews 7.11–12, 20–22, 27
Hebrews 8.1-2, 6-13
“The quotation of Jer. 31:31–34 (LXX 38:31–34) is the longest quotation in the NT, yet the author of Hebrews follows with a surprisingly brief comment, focusing solely on the word “new”… In short, the author understands this rich passage from Jeremiah as a direct verbal prophecy, fulfilled by the inauguration of the new covenant in Christ’s sacrificial death and his triumphant exaltation to service as superior high priest. It is that new covenant, established by a superior offering, by which people can know God, have his laws written on heart and mind, and have their sins decisively forgiven.” 
Hebrews 9.11–12, 15, 18-20, 24-26
Steven J. Wellum:
“By setting Christ’s death in its new covenant context, he argues from covenant inauguration for the necessity of Christ’s cross (Heb 9.15-22). In 9.15, he states, “for this reason,” which establishes a strong causal relationship between 9.11-14 and 9.15. Jesus not only fulfilled the priesthood-sacrifice of the old covenant, but he also fulfilled the covenant itself, thus bringing it to its God-appointed telos. Jesus’s death is viewed as a covenant sacrifice, a representative death, first, for those under the penalties of the old covenant—“as a ransom to set free from the sins committed under the first covenant” (9.15)—and, second, as the judicial grounds for the inauguration of the new covenant, which is bound up with the full forgiveness of sin.”
Hebrews 10.1, 8-22
“With an authoritative “the Lord says” the pastor begins his summary of the benefits brought by the New Covenant promised in Jeremiah and fulfilled by Christ. He has selected the first (Jer 31:33b; Heb 8:10b) and last (Jer 31:34d; Heb 8:12b) benefits enumerated in that promise as most directly attesting the effectiveness of Christ’s sacrifice in removing sins. There can be no doubt that he affirmed the reality of the intervening description of how God’s people would “know” him (Jer 31:33c–34c; Heb 8:10c–12a).” 
The Old Covenant Is No Longer in Effect
Christ’s death not only ratified the new covenant, it also ended the obligation to keep the old for Jews and Gentiles (who were never under obligation to keep the law anyhow). Here are 10 key texts that teach the old covenant is no longer in effect for those who are in Christ.
- Gal 2.21 “…if righteousness were through the law, then Christ died for no purpose.”
- Gal 3.21–25 “Now before faith came, we were held captive under the law…the law was our guardian until Christ came…but now that faith has come, we are no longer under a guardian”
- Gal 4.21–5.1 “…we are not children of the slave [Hagar = Mt. Sinai] but of the free woman [Sarah = Jerusalem above]. For freedom Christ has set us free [from the law]; stand firm therefore, and do not submit again to a yoke of slavery”
- Gal 5.18 “But if you are led by the spirit, you are not under the law.”
- Rom 6.14 “…you are not under law but under grace”
- Rom 7.1-6 “the law is binding on a person only as long as he lives…you also have died to the law through the body of Christ…now we are released from the law, having died…so that we serve in the new way of
- Rom 10.4 “For Christ is the end of the law for righteousness to everyone who believes.”
- 2 Cor 3.6–18 “[God]...made us…ministers of a new covenant, not of the letter but of the spirit. For the letter kills, but the spirit gives life…where the spirit of the Lord is, there is freedom
- Eph 2.13-15 Christ…has broken down in his flesh the dividing wall of hostility by abolishing the law
- Col 2.13–17 “God…cancel[ed] the record of debt that stood against us with its legal demands…nailing it to the cross…therefore let no one pass judgment on you in questions of food and drink, or with regard to a festival or a new moon or a Sabbath. These are a shadow of the things to come, but the substance belongs
In addition to no longer keeping the old covenant, the new covenant also provides us access to God in a whole new way (Eph 2.13-18). Furthermore, as 2 Corinthians 3 makes clear, God’s spirit is intrinsic to our experience of the new covenant—a topic we, sadly, do not have time to explore here. However, we must be careful not to take this access, forgiveness, inclusion, spirit, etc. for granted. In fact, we should take the new covenant even more seriously than the old covenant.
Hebrew 10.28-29; 12.18-24
Now that we have seen how the Christ event (death, resurrection, ascension) has fulfilled and brought the old covenant to an end while also inaugurating the new covenant, we must ask a new question. What about Israel? Are they still under the old covenant? How should we understand the relationship of Israel and the Church? To this we will turn our attention next time.
 George H. Guthrie, “Hebrews,” in Commentary on the New Testament Use of the Old Testament. ed. G. K. Beale and D. A. Carson (Grand Rapids: Baker Academic, 2007), 972.
 Peter J. Gentry and Steven J. Wellum, Kingdom through Covenant, 2nd ed. (Wheaton, IL: Crossway, 2018), 730.
 Gareth Lee Cockerill, The Epistle to the Hebrews, New International Commentary on the New Testament (Grand Rapids: Wm. B. Eerdmans, 2012), 456.