Jer 33:31-32 is arguably the most important declaration in the Old Testament; that God will one day make a New Covenant (a New Testament) with his people. Because Israel repeatedly ‘broke’ the covenant made at Sinai, God will one day ‘put my law in their minds and write it on their hearts’ (v. 33). This does not suggest God will grant his people greater strength to obey his law. It suggests God will give his people a new motivation to WANT to follow it. But how?
Under the old covenant, the Israelites were commanded to offer sacrifices for their sins. Day after day, year after year, the Israelites were reminded that they had to atone for their sins BEFORE coming into the presence of a holy God, or they would be burned up by his holiness. As such, the Israelites’ motivation to obey the law – either through not breaking it (which was impossible) or offering sacrifices when they did – was to come into God’s presence.
In Luke 22:20, Jesus announces that he inaugurates the new covenant with his death on the cross. This brought the end to the sacrificial system, in that Jesus’ death atoned for ALL the sins of God’s people, once and for all. Jesus has fulfilled the law for his people, both in following it perfectly on our behalf, and atoning for the sins of those who break it.
This means God’s people no longer have to follow God’s law to come into his presence. Christians follow God’s law for an entirely new reason; overwhelming gratitude. When we reflect on the infinite price Jesus paid to atone for our sins, it makes us WANT to please him through following his law. As the famous hymn ‘Be thou my vision’ says; ‘Oh to grace how great a debtor, daily I’m constrained to be’.
