I just watched the fourth session of Battling Unbelief. It may be a little hard to understand at the beginning, but it is an absolute gold. Buy it or borrow it. Watch it, learn from it, and repent and trust in God's never-ending grace.
What did I learn?
Simply put, faith and gratitude, both are indispensible in the life of a Christian. However, it is faith, not gratitude that produces good works. (Watch the dvd to understand the full meaning of this sentence!)
I have spoken out of ignorance just a few days ago, that we do good works as Christians because we are thankful to God, in a conversation with a muslim work colleague. Given the context of the whole conversation, that was not a completely wrong answer I believe, but Oh, how I regret that moment, and I wish I had made a better, more accurate, more convincing answer to him.