I meant verse 21. Paul gives his opinion that if justification/righteousness was obtainable through the Law then his religion is void.
Luke in the opening of his gospel describes two Jews as “righteous” before God due to their faultless obedience of the Law. Paul’s religion therefore is null and void and totally unnecessary.
Luke 1:5-7 New Revised Standard Version (NRSV)
5 In the days of King Herod of Judea, there was a priest named Zechariah, who belonged to the priestly order of Abijah. His wife was a descendant of Aaron, and her name was Elizabeth. 6 Both of them were righteous before God, living blamelessly according to all the commandments and regulations of the Lord. 7 But they had no children, because Elizabeth was barren, and both were getting on in years.