I think I was a bit unclear last week at RUF. Here is a more simplified version of what I was saying:
In Luke 17-18, Jesus is teaching about faith, and what he has to say about it is unique to our instincts. We often think having faith is a sign of personal strength. Faith reveals how strong you are amidst difficult situations, its what you turn to when things get hard.
When Jesus, describing what it means to follow him, says that you must be prepared to forgive people who wrong you over and over again, the disciples respond "increase our Faith!" This seems like a wise and reasonable response, and maybe something you and I should pray along with them. But what are they really saying to Jesus? The disciples are admitting that Jesus' command sounds difficult, and they are not stronger enough to do it, so they are asking for more strength. But Jesus turns around and says you don't need 'more strength', you only need a little. Jesus is saying that you don't need big faith in your little self to be a radically forgiving person. He is saying you only need a little faith in a big gospel to be a radically forgiving person. Jesus' view of faith is calling us to stop looking within, and to really begin looking outside of ourselves, looking at Jesus and God's gracious forgiveness through the cross. Genuine faith is actually an expression of weakness. It is actually saying "I've got nothing within me that will help here, so I look over there for strength."
This is developed further by Jesus in the parable of the tax-collector and the Pharisee, Jesus commends the tax-collector (a social/spiritual outsider) because his posture towards God was complete unworthiness and utter helplessness. The tax-collector stands before God and screams "I am weak". Meanwhile the Pharisee thinks he has genuine faith and commends himself. Quickly speaking, the Pharisee looks within, at his own obedience and good works, and draws his "faith" from such things. Jesus infers that this 'good' Pharisee is not the one who is Justified before God, and it is his faith in himself, his lack of need, that keeps him away. The truly sad irony is that the Pharisee believes what he is doing will draw him close to God, but it is actually keeping him further and further away.
What Jesus is really teaching here is that Faith is fundamentally an expression of weakness and need. Faith is coming to reality, the end of your moral-achieving rope, and saying "if someone doesn't intervene, I'm screwed." Jesus' words about the Pharisee do not teach us that faith is antithetical to good works (in fact in many other places Jesus, with other biblical writers, says that good works are the true expression of believing faith), but that there is a true danger of your goodness blinding you to the need of salvation. Faith is not the expression of a need to be a better person, it is an expression of a need for salvation. The former says "I have a few issues that need to be corrected", the latter says "I am messed up through and through, I can't do anything about it, someone needs to change me." Faith says "I am weak." But the beautiful irony of the gospel is that when you say you are weak, you actually become strong. Jesus says the way to become exalted is to be humbled. If you go looking for exaltation, you'll never find it nor will you ever get it. But genuine faith is actually strong, b/c you are no longer relying on yourself, but on Jesus who became weak and then was resurrected in power from the dead so that you could become free and then justified before God. See, This free's you up to finally being honest and be authentic about what's really going on in your life. Jesus is teaching here that faith really doesn't work for people who don't want to be authentic (ie the Pharisee). He wants you to be open, honest, and weak - expressing your need for him. That's not just what faith is for, thats what genuine faith is, and it makes you strong.