Lukewarm Christians?

Why does God's saving grace allow so many to live as lukewarm Christians? If we are saved by grace then what does it matter how we live?
Pastor Mark Driscoll answers this question as part of a live "Ask Anything" session in which audience members SMS questions to the pulpit to be answered in real time.

This question was answered in the broader context of a sermon entitled "Grace" which can be found at http://www.marshillchurch.org/media/r...