There are two kinds of religious people: Those who believe they can make themselves acceptable to God, and those who know they can't, but hope He will accept them anyway. A Christian must always be the latter.
In my opinion, the parable of the Pharisee and the Tax Collector should be preached in every congregation at least once a month. I have stated this before, and recognise the irony in that I have since failed to do so in my own ministry work, but I firmly believe it: It is an important parable which exemplifies the attitude we, as Christians, should have, as well as condemning the incorrect attitude Christians are stereotyped to have.
In the unbelieving world, Christians are seen as being extremely judgemental, hypocritical and arrogant. And indeed, many professing Christians are. But in the parable of the Pharisee and the Tax Collector, Jesus says that the "holier than thou" attitude is the best way to secure a ticket to Hell. In the parable, the Pharisee boasts of his greatness and belittles the tax collector. The tax collector, by contrast, doesn't even acknowledge the Pharisee. He knows he's a wretch, but he also knows something the Pharisee doesn't: God is full of grace. And so the tax collector humbles himself and asks for only one thing: "God, have mercy on me, a sinner."
This tax collector shows all the signs of genuine repentance. He doesn't approach the alter, doesn't look to Heaven, he beats his chest in despair, this man knows he is worth nothing before God. But because of this, God treats him as if he is worth everything. Even His Son's own life.
There are doctrines, denominations, even whole religions in the world today which claim to be Christian, and yet, because they preach that salvation is not by grace alone through faith alone, they are as worthless as the faith of the Pharisee. Our righteousness, according to the prophet Isaiah 64:6, is nothing but filthy rags, because of our sin. What can we hope to offer God? Nothing. Christ, and Christ alone, can offer the Lord a tribute worthy to earn us an inheritance in Heaven. This can only be claimed by humility. To the rest, you will not go down to your house justified. If pride goes before a fall, there is a fall your pride was never worth going before.