Interpretations

I was having a conversation with someone recently relating to following what the Bible says.
While I am very much on the other side of the church fence at the moment it's always been my belief that, while some interpretation can be made, if you are a believer then you follow the word of God.
What surprised me was the view that just because it says something in there you can interpret it pretty much to suit yourself.
What puzzles me is if that is true then what importance does the word of God have to you?
If you believe the Bible is the word of God but that it can be twisted to suit yourself then what are you actually believing in - some kind of user-friendly deity that makes you feel better that you can say you follow without having to commit to it?
Sounds a bit dodgy to me.
Now I must say that I don't think the person I was talking with about this believes in this way and I think I made a valid point.
If the Bible says you shouldn't steal and you believe the Bible is the word of God then it follows that you shouldn't steal. You can't get around that.
Sure there are plenty of contextual things in the book but if everything is open for interpretation then what are you actually supposed to believe?