ROMANS 4: 1-8

In the preceding paragraph (3:21-31) Paul has been proclaiming a righteousness from God, and therefore valid before God, because it does not in any way depend on human merit. He stated that the Law and the Prophets, or Holy Scripture, had already borne witness to this righteousness (3:21). Paul will now develop the point by Old Testament precedent and example. He does so through the use of the patriarch Abraham, pointing to him as an illustration of how one becomes righteous. The Jews regarded Abraham as the great founder of the race and the pattern of all that a man should be.
Abraham was righteous before God. But what was the grounds of Abraham's righteousness, faith, or works? The answer of Jewish tradition was works, but Scripture says Abraham's righteousness was by faith. Paul proves that the doctrine of justification by faith is as old as the Jewish nation itself (CIT).

I. Belief in God Justifies, 1-3.
II. Righteousness For the Ungodly, 4-5.
III. Forgiveness Not Works, 6-8.

The Jews were proud to be called children of Abraham. So starting in verse 1 Paul uses Abraham as an example of someone saved by faith. "What then shall we say that Abraham, our forefather according to the flesh has found?"
What then shall we say? Paul is fond of this rhetorical question which anticipates an objection and proposes an inference (4:1, 6:1, 7:7, 8:31, 9:14,30). This question connects the preceding reasoning of how justification is obtained with the illustration of Abraham.
Abraham, the founder of the Nation of Israel, was the man to whom God first spoke the promises. He was the man who in a unique way had been chosen by God and who had heard and obeyed Him. God had called Abraham to leave home, friends, kindred, and livelihood. Hebrews 11:8 says that Abraham did not argue, did not hesitate, but followed God's Word not knowing where it would lead him. It was Abraham's faith in believing God, which his works or actions substantiated, that resulted in God justifying him. Abraham was not saved by his works, but by His faith in God which cause him to follow God.
What made Abraham different from other people? Why was Abraham chosen by God to be the ancestor of God's special people? Paul is going to show that what Abraham found (or discovered, heur kenai) is "justification by faith."

Verse 2 discusses the nature or manner of Abraham's justification before God. "For if Abraham was justified by (out of) works, he has something to boast about, but not before God."
How did Abraham obtain acceptance with God? The Rabbis insisted that it was because of his works that Abraham was chosen. They developed the doctrine of salvation by human merit. So Paul attacks the very fortress of the doctrine's strength, which is the story of Abraham, who according to the Jews had earned his way into God's good pleasure. The Rabbis even had a doctrine that Abraham had an excess of credits because of his works