I'm not saying that the Bible shouldn't be used to explain God or how to live. I do think that it shouldn't be the only thing we use. Thinking about this more though, I can understand why we do use the bible so much.
For anyone who has accepted Christ, the bible is the place to look for answers and refresh our faith. I do think Christians spend far too little time actually reading the bible. While we definitely don't need to spout off bible verses at the drop of a hat (the more I'm in seminary the more I see people do this . . . I guess that makes them more faithful than I) we do need to understand what the bible says and try to see how it applies to our life.
I talk to a lot of people who what to believe in God, or really do understand that He exists. At the same time they see the bible more as general stories passed on instead of factual events. They are stories to explain life.
Maybe the reason we talk about the bible so much is because we do recognize that it's the best source on how to live. In some cases it's the only source of our history.
There is no way that we can ever force someone to believe in God. We can't convince them through proof or explanation. A person's relationship with God is between that person and God. There's nothing I can do directly to change that path.
So, maybe it's okay that we use the bible as our evidence. We've decided that we have faith in something we cannot see, and in that faith we accept a book which can't be unilaterally proven (yet).
All we can do is live each day in that faith and following that book. We'll let God help those others who aren't quite there yet.