One problem is that so many unbelievers quote the bible out of context out of ignorance, and so many believers quote the bible back to them in an attempt to teach them something!

As soon as you start making an argument from a source of authority, you need to stay with it, and your opponent can attack the credibility of that source. Your entire argument can be waylaid by your opponent because he can say something idiotic like, "the Gospels were all written by Constantine 300 years after Christ", and you then have spend all your time telling him how and why he's wrong about that, instead of focusing on your argument.

We are living in a post-Christian world... There ARE other sources of truth than the Bible, and if people really want to evangelize, they need to draw people in using a method that will make sense to their target audience. I prefer to use science and logic and history, because we live in an age when so many people call themselves rational, and believe strongly (almost religiously) in rationalism. They believe in Truth, and you can use this belief to draw them closer to the Source of that truth. But for heaven's sake, quoting the bible is not evangelization.

(That said, I verymuch appreciate any thread with a daily bible verse in it :)