Luke 18:13

"But" introduces the striking contrast between the two individuals. The tax gatherer’s geographical distance from the Pharisee symbolized the difference. His unwillingness to lift his eyes, much less his hands, to heaven in prayer pictures his feeling of unworthiness (cf. Psalms 123:1; Mark 6:41; Mark 7:34; John 11:41; John 17:1). Beating his chest expressed contrition, which he articulated in his prayer. He did not boast of his own righteousness but pled with God for mercy acknowledging his sin (cf. Psalms 51). He used God as the standard of righteousness and confessed that he fell short. He knew that his only hope was God’s mercy. The Pharisee felt no need and voiced no petition, whereas the publican felt nothing but need and voiced only petition. [Note: Ibid., 2:292.]

"This parable is really the parable of the two prayers. In those prayers appear two kinds of hearts, whose contrast is not only seen in the way they make their request, but also in the way they approach God." [Note: Bock, Luke, pp. 460-61.]

Literally the publican asked God to be propitious (Gr. hilaskomai) or satisfied. Since Jesus made propitiation (satisfaction) for the sins of humankind on the Cross no one needs to pray this prayer today. However when the tax collector prayed it propitiation through Jesus Christ’s blood was not yet available. It is, of course, permissible today to ask God to be merciful to us as sinners, but we need to remember that He has already done that through Jesus Christ. The good news of the gospel is that God is propitious (satisfied; cf. 1 John 2:2).

"Merciful" is a translation of the ". . . Greek hilaskomai, used in the Septuagint and N.T. in connection with the mercy seat (Exodus 25:17-18; Exodus 25:21; Hebrews 9:5). An instructed Jew, the tax collector was thinking, not of mercy alone, but of the blood-sprinkled mercy seat (Leviticus 16:5 . . .). His prayer might be paraphrased, ’Be toward me as thou art when thou lookest upon the atoning blood.’ The Bible knows nothing of divine forgiveness apart from sacrifice . . ." [Note: The New Scofield Reference Bible, p. 1108.]