For if the inheritance is of the law, it is no more of promise: but God gave it to Abraham by promise.
All Commentaries on Galatians 3:18 Go To Galatians 3
Ambrosiaster
AD 400
The Jews maintain two opposing tenets. For in no way and by no argument can they be persuaded that the promise to Abraham was rendered void by the law, and they are right. But in their shortsighted vanity they maintain another contrary principle, thinking that justification could not come without the practice of the law. They know that Abraham, who is the type [of justification], was justified through faith alone, without the practice of the law…. The heirs to the promise of Abraham are therefore those who are his successors in the adoption of the faith by which Abraham was blessed and justified. The testimony of the promise to Abraham is therefore called a covenant [to signify] that after his death there would be heirs in the promise, made sons of Abraham through faith. –.
