Previously in Romans
Paul showed that all are without excuse, and need salvation from God's wrath (1:16-3:20). God demonstrated his favor and righteousness by rescuing believers through the atoning sacrifice of Jesus, freely acquitting them from sin (3:21-31).
Paul wrote that this acquittal from sin, justification, comes by faith and not by works of the law (3:28).
Romans 4 Outline
Justification by faith illustrated
Abraham counted as righteous
David rejoiced in God's forgiveness
Abraham esteemed righteous before circumcision
God's promise to Abraham
Promise came through faith, not law
Guaranteed to all Abraham's offspring, including faithful Gentiles
Abraham's unshakable hope and faith
Faith credited to Abraham as righteousness
Abraham's life was recorded in Genesis 11:27 to 25:11. God sent Abram from his family in Ur to the promised land of Canaan (Genesis 12:1-6). God made him a father of nations, and gave him the name Abraham which means "father of a multitude" (Genesis 17:1-8).
Abraham fully trusted God. He believed what God said and acted on his convictions. Believing God's promise to make him a great nation, Abram moved to a foreign country (Genesis 12:1-5).
When God told Abram his offspring would be numberless like the stars, he believed God, and it was counted to him as righteousness (Genesis 15:5-6).
Abraham's willingness to sacrifice Isaac at God's command demonstrated faith and obedience (Genesis 22).
The rite of circumcision was instituted by God to signify a covenant relationship between God and Abraham (Genesis 17:10-27). Jews practiced circumcision in New Testament times. Christians were not directed to be circumcised (Acts 15:5-11). God desired circumcision of the heart, trust in him and obedience to his will (Jeremiah 9:25-26, Romans 2:29).