First-century Judaism was diverse in many ways, but there were some things on which virtually every Jew was agreed. For example, tax collectors were generally regarded as traitors to Israel for their willingness to take part in the funding of the occupying Roman forces in Palestine by collecting taxes. The Pharisees, on the other hand, were almost universally respected by the Jews because of their devotion to the law of God. Jewish men and women saw them as particularly holy, because they focused so intently on the minutiae of the Mosaic law that their outward manner of life was noticeably different from that of the common person.
Certainly, the concern to know and keep the law of God is commendable. However, if one is not careful, one can jump from being concerned to follow the law to the belief that one has a better standing before God because of one’s obedience. That was the trap that most of the Pharisees fell into. Many of them, like the Pharisee in today’s passage, “trusted in themselves that they were righteous and treated others with contempt” (Luke 18:9).
In the parable of the Pharisee and the tax collector, Jesus gives a strong rebuke to those who trust in their own righteousness before the Lord. Somewhat ironically, Christ concludes that it is not the most devoted law-keeper that is justified—declared righteous—before God; rather, the person whom God declares righteous recognizes His own unrighteousness and turns to the Lord for mercy (vv. 10–14).
The Pharisee in Jesus’ parable erred because He did not understand God’s standard for righteousness. The Lord does not grade on a curve. Contrary to the Pharisee’s belief, it is not that God accepts one person and not another because the one has not committed as many heinous sins as the other. Neither does the Lord justify one person and not another because the former is more scrupulous in his obedience than the latter (vv. 11–12). No, if people want to be justified—declared righteous—by keeping the law, the standard is absolute perfection. It is not enough to keep just one commandment for justification—you must keep them all (Gal. 5:3). It is a deadly proposition for sinners, for no sinner can keep God’s law perfectly.
Why was the tax collector justified and not the Pharisee? Because the tax collector recognized His unrighteousness and His inability to make Himself righteous before God, turning to God’s mercy alone. That’s the only way a sinner can be justified.