What Does It Mean to Have Faith? Romans 4

In Romans 4 Paul spends the chapter talking about the most important figure in the Jewish faith, Abraham. This gives further credence that the primary audience for the letter to the Romans were Jewish by background.  Though Abraham preceded Jesus, Abraham was still credit with righteousness by faith.  Abraham believe in God's promises which made him right with God.

16 So the promise is received by faith. It is given as a free gift. And we are all certain to receive it, whether or not we live according to the law of Moses, if we have faith like Abraham’s. For Abraham is the father of all who believe. 17 That is what the Scriptures mean when God told him, “I have made you the father of many nations.”This happened because Abraham believed in the God who brings the dead back to life and who creates new things out of nothing.

Paul spends a lot of time comparing works to faith.  He argues that one works they get paid for what they do out of obligation.  But the difference in trusting in a promise is that you are trusting in the one who is making the promise.  When God called Abraham to leave his homeland and journey to Canaan, Abraham trusted in faith and went with his family and all his belongings.  The Jews received the law of Moses which only pointed out that they could never measure up to God's standard of righteousness which was perfection.  So faith is a gift given we can't earn it, but we exercise faith when we trust in God's promises. Abraham became the father of many "nations". This meant people of all ethnicities and those who were considered Gentiles.

18 Even when there was no reason for hope, Abraham kept hoping—believing that he would become the father of many nations. For God had said to him, “That’s how many descendants you will have!”[e] 19 And Abraham’s faith did not weaken, even though, at about 100 years of age, he figured his body was as good as dead—and so was Sarah’s womb.

The greatest act of faith was when Abraham trusted that he would have a child at 100 years old.  His wife Sarah was not far behind at 90 years old.  Abraham exercised great faith because he still trusted that he would be given a son to become a father of many nations.   Of course Abraham's faith was not always perfect.  Remember when he went to his maidservant Hagar to provide him a child, she bore him Ishmael.  This was a lack of faith but God still used him though his faith wasn't always perfect. 

20 Abraham never wavered in believing God’s promise. In fact, his faith grew stronger, and in this he brought glory to God. 21 He was fully convinced that God is able to do whatever he promises. 22 And because of Abraham’s faith, God counted him as righteous. 23 And when God counted him as righteous, it wasn’t just for Abraham’s benefit. It was recorded 24 for our benefit, too, assuring us that God will also count us as righteous if we believe in him, the one who raised Jesus our Lord from the dead. 25 He was handed over to die because of our sins, and he was raised to life to make us right with God.