The Meaning of Galatians 3:15-18: Promise Before Law

Context and Explanation of Galatians 3:15-18

Now that we’ve seen Paul emphasize faith over law in the opening of Galatians 3, he now strengthens his case with a historical and legal argument.

Paul is writing to the Galatian churches - mostly Gentile believers - who are being pressured by some teachers to follow Jewish laws like circumcision to be fully accepted by God. These verses come right after Paul’s reminder that Abraham was made right with God by faith, not by law, and now he uses a simple human example: once a covenant or agreement is signed, no one can change it later. The promise God made to Abraham came 430 years before the Law of Moses, so the Law cannot cancel or alter that original promise.

Instead, the Law was added later to show people their sin, but it never replaced God’s promise - salvation has always been by faith in Christ, the true descendant of Abraham.

Law vs. Promise: Why God's Covenant with Abraham Can't Be Changed

Having established that faith, not law, is the foundation of our relationship with God, Paul now digs deeper into how God's original promise to Abraham sets the stage for salvation by grace alone.

Paul makes a powerful legal and theological argument: once a covenant is sealed, it cannot be altered. He uses a human example to show that even our own agreements are binding once ratified - so how much more is God’s covenant unchangeable? The promise to Abraham came 430 years before the Law was given through Moses, which means the Law cannot cancel or modify that earlier promise. If it did, God would be going back on His word, which contradicts His unchanging nature.

The key word here is 'offspring' - a singular term referring not to many descendants, but to one: Christ. This is a divine revelation. It is not merely a grammatical point. Paul highlights that the blessing promised to Abraham was always meant to flow through one ultimate descendant, Jesus (Galatians 3:16). This redefines Jewish identity - not by lineage or law-keeping, but by union with Christ. And if the promise is fulfilled in Him, then salvation comes through faith in Him, not through works of the Law.

This shows that the Law was never God’s plan for salvation. Instead, it served a temporary role - exposing sin and pointing people to the need for a Savior. Now that Christ has come, we are no longer under that guardian (Galatians 3:24-25). The promise stands fulfilled in Him, and all who belong to Christ are heirs of Abraham by faith.

The law was never meant to save - it was meant to show us we need a Savior.

This leads directly into Paul’s next question: if the Law isn’t for salvation, then why was it given at all? That’s the issue he tackles in the following verses.

Living by Promise: How Faith, Not Rules, Brings God's Blessing Today

Now that we’ve seen how God’s promise to Abraham stands firm in Christ and cannot be undone by the law, we can apply this truth to our own lives today.

The good news is simple: we don’t have to earn God’s favor by keeping rules or making ourselves good enough. Just like Abraham, we’re made right with God by faith - by trusting what He has promised through Jesus. This was a radical idea for many in Galatia who thought obeying the law was necessary for salvation, but it’s the heart of the gospel: grace, not effort, brings us into God’s family.

We receive God’s promise by trusting Him, not by trying to earn it.

This truth frees us to live not under pressure to perform, but in confidence that God keeps His promises. And it prepares us for Paul’s next point: if we’re not saved by the law, then what was the law’s purpose in the first place?

The Promise Fulfilled: How We Become Abraham's Family Today

This promise is the foundation of who we are today as God's people through faith in Christ, not merely ancient history.

Galatians 3:29 makes it personal: 'And if you are Christ's, then you are Abraham's offspring, heirs according to promise.' This means that anyone - Jew or Gentile, slave or free, from any nation - who trusts in Jesus, is now part of Abraham’s spiritual family and shares in God’s promise. Being united with Christ, not ethnicity or religious rituals, is what matters. Romans 4 shows Abraham was made right with God by faith before any law existed, and Hebrews 6:13-18 confirms God’s promise is guaranteed by His unchanging oath.

If you belong to Christ, you are Abraham’s true family, no matter your past or background.

So in everyday life, this truth should humble us - no one earns their place - and inspire radical welcome in our churches, where all believers stand equal in Christ. This shared identity in the promise prepares us to understand what Paul says next about the law’s temporary role and how it led us to Christ.

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