What did God tell Abraham to do when he called him?
God told Abraham to leave the city of Ur, leave his family, and go to the place God would show him. Abraham believed God, and that belief became faith, not merely believing in God. Paul uses this to show Abraham was declared righteous only because he believed God.
Les teaches that Abraham was steeped in idolatry as a young man in the city of Ur. God reached down in grace and told him to leave the city, leave his family, and go to a place that He would show him. Abraham believed God, and Les puts two statements on the board to show the vast difference between believing God, which becomes faith, and simply believing in God, which is only recognizing that He exists but not having anything to do with Him. Paul then builds his case in Romans 4:5 that Abraham was declared righteous only because he believed God.