"Two men went up into the temple to pray, one a Pharisee and the other a tax collector. The Pharisee, standing by himself, prayed thus: 'God, I thank you that I am not like other men, extortioners, unjust, adulterers, or even like this tax collector. I fast twice a week; I give tithes of all that I get.' But the tax collector, standing far off, would not even lift up his eyes to heaven, but beat his breast, saying, 'God, be merciful to me, a sinner!' I tell you, this man went down to his house justified, rather than the other. For everyone who exalts himself will be humbled, but the one who humbles himself will be exalted." (Luke 18:10-14)
Have you ever noticed the points of comparison in this parable? The Pharisee compares himself with "other men" and even with the tax collecter also standing in the temple to make the point to God that, relatively speaking, he is a good man. He is looking around at the world and knows that he is "not like other men, extortioners, unjust, adulterers" and he is justified in his heart by this, in fact he was justified to himself before he even started to pray (this is why he thanks God for his good standing), but he is not justified before God so his justification means nothing. The tax collector also makes a point of comparison, but he compares himself to God and so he prays, "God, be merciful to me, a sinner!" He is unwilling even "to lift up his eyes to heaven" because he is painfully aware of his own unworthiness. Clearly since Jesus himself says regarding the tax collector, "This man went down to his house justified" then the tax collector's attitude is the one worthy of emulation. Like him, we should remember to compare ourselves with God and go out into the world ashamed of our own imperfections, but understanding that "It is God who justifies. Who is to condemn?" (Rom. 8:33-34)