Jesus directed his parable about the Pharisee and the tax collector "To some who were confident of their own righteousness and looked down on everyone else." (Luke 18:9-14) When the Pharisee prayed, he paraded all his deeds before God. He was giving God a gentle reminded that he was a good man, a moral man: he fasted twice a week and contributed a tenth of his income. And he was especially pleased that he was not like the tax collector. Tax collectors were notorious for corruption. The tone of his voice revealed just how pleased he was with himself. Yes, he deserved to go to heaven.
In contrast to the Pharisee, the tax collector "stood at a distance. He would not even look up to heaven, but beat his breast and said, 'God have mercy on me, a sinner.'" And Jesus said that the tax collector "rather than the other [Pharisee] went home justified before God."
The problem the Pharisee had was not that he didn't try hard enough to be good, he did, but his trust was in what he was doing to secure him his place in heaven. He was going to save himself. Whereas the tax collector acknowledged that he was spiritually bankrupt, with nothing to recommend him, and threw himself upon the mercy of God.
Two men, two sinners, one trusting in himself the other trusting in the mercy of God. Two different results: one person lost and the other saved.
Trusting God's Righteousness
The futile attempt to make oneself right with God is expressed by Paul as he laments the lost condition of his fellow countrymen: "Dear brothers and sisters, the longing of my heart and prayer to God is that the Jewish people might be saved. I know what enthusiasm they have for God, but it is misdirected zeal. For they don't understand God's way of making people right with himself. Indeed they are clinging to their own way of getting right with God by trying to keep the law. They won't go along with God's way. For Christ has accomplished the whole purpose of the law. All who believe in him are made right with God." (Romans 10:1-4)
These people not only believed in God but were zealous for him, yet they were lost (hence Paul's prayer that they might be saved). How could such people be lost?
Their problem, like so many today, was this: they did not know how God accounts a sinner right with him and, as a result, they set about establishing their own righteousness. In other words, they would make themselves right with God. They were attempting the impossible.
None of us can save ourselves by producing a standard of righteousness acceptable to God. In his love and mercy for us, God has provided us with a Saviour who has done for us what we could never have done for ourselves. He is our righteousness. We must depend on him, not on ourselves.