The Basis of Justification: Faith not Works

So argues Paul in Romans 4.2,3ff. Paul points out that his message is the same message of the Pentateuch when it says that Abraham believed God and it was reckoned to him as righteousness. Paul then points out that his message is the same as David who also proclaimed that righteousness before God came apart from works. Paul then, agrees with Moses and David on the nature of justification.

Chrysostom is very helpful here: There are two kinds of boasting—one of works and one of faith…. Paul’s great strength is particularly displayed in this, that he turns the objection around and shows that what seemed to favor the idea of salvation by works (viz., boasting) belonged much more truly to salvation by faith. For the man who boasts in his works is boasting about himself, but the man who finds his honor in having faith in God has a much better reason for boasting, because he is boasting about God, not about himself.