How did St. Paul use Abraham in his argument about faith in Galatians?

In his Letter to the Galatians, St. Paul uses the figure of Abraham to argue that justification comes through faith rather than adherence to the Jewish law.12

Paul employs Abraham’s story to challenge the requirement of circumcision for his Gentile converts. His argument centers on the following points:1

• Faith as the Basis for Righteousness: Paul cites Genesis 15:6, noting that Abraham "believed God, and it was reckoned to him as righteousness". By emphasizing this, Paul establishes that religious identity is rooted in belief rather than ethnicity or ancestry.3
• Inclusion of Gentiles: Paul argues that because Abraham was justified by faith, those who share that same faith—including Gentiles—are the true descendants of Abraham and are "blessed with Abraham who believed".3
• Priority of the Promise: Paul points out that the covenant promise was made to Abraham and his "seed" (interpreted as Christ) long before the Law was given to Moses 430 years later. Therefore, the Law is not eternal and cannot supersede the original promise.2

Ultimately, Paul concludes that all who belong to Christ are Abraham’s offspring and heirs according to the promise, rendering the traditional requirements of the Law unnecessary for salvation.23