Job then warns the men of the danger of speaking falsely for God--even when you're trying to slant things in his favor. The NLT version I was reading put it this way: "Are you defending God by means of lies and dishonest arguments?" The NIV says, "Will you speak wickedly on God's behalf? Will you speak deceitfully for him?" According to Job, God doesn't like you speaking for Him and getting it wrong, even if you're doing it out of good intentions. Job says "you will be in serious trouble with him if even in your hearts you slant your testimony in his favor."
As a writer who hopes to demonstrate Christian principles through her stories (and even on this little blog), I took this warning to heart. My characters often talk about God's nature and what he would want them to do in a given situation. It's a solemn thing to "speak for God" that way, even in a fluffy little fiction story.
I've heard a similar warning put another way, something like, "Never make yourself out to be more merciful than God." I remember after Hurricane Katrina, how so many people were eager to speak up for God and absolve him of any "wrongdoing." God doesn't want innocent people to suffer, they said, and so the storm wasn't his will. He would never allow such a thing to happen. By the time these well-meaning folks got through, the god they were defending didn't seem to have much power of any kind. That's slanting things in God's favor--and taking him out of control in the process. It's assuming we know as much as God and always know what he's doing. Let me state for the record that I have no idea why Hurricane Katrina occurred--but I still believe God is sovereign and in complete control.
Those of us who write fiction sometimes put our poor characters through trials that would make Job lose patience. Those characters want to know why God is doing these things to them, and all of a sudden, we find ourselves speaking for God through our work. After reading Job 13, that's quite a humbling thought for me.