Abraham’s faith was righteous faith. What made his faith righteous was that God was the object of it. But Abraham exercised his faith and it was counted (imputed, reckoned) to him for righteousness. The exercising of his faith did not render him righteous, it declared, or published that he was righteous. When we exercise our faith, and believe in Him that raised up Jesus our Lord from the dead, the same righteousness will be imputed to us also.
(Note: In this sermon, I mistakenly attributed the opening of the “door of faith” as being said by Peter, when it actually was said by the Apostle Paul and Barnabas in Acts 14:27 to the saints at Antioch.)