On the Redeemer site are free sermons related to Tim Keller's book The Reason for God. Enjoy! And go look at the rest of my Tim Keller Resources. (via)
The Trouble with Christianity: Why it's so Hard to Believe it
Exclusivity: How an there be just one true religion?
Suffering: If God is good, why is there so much evil in the world?
Absolutism: Don't we all have to find truth for ourselves
Injustice: Hasn't Christianity been an instrument for oppression?
Hell: Isn't the God of Christianity an angry Judge?
Doubt: What should I do with my doubts?
Literalism: Isn't the Bible historically unreliable and regressive?