Why does God get mad?

Stupid question;
If God knows all.  If God has written history from the beginning of time until the end of time, why does he get so angry when man screws up?  He already knows that they're going to disappoint him and turn away from him repeatedly.  He made them that way.

Just wondering, so enlighten me!

Fun Question of the Day

I'm reading Chronicles now.  It's all begats at the moment and I can skim over it so the suffering is low.

It got me to thinking.  Heaven and Hell have not been quantified yet in the OT.  So, what has happened to the cast of characters that we've read about so far?  Are they just dead and soulless since God hasn't created the rules for the afterlife?  Are they just hanging out in limbo waiting for God to open up the gates?

Will they have to accept Jesus as their savior?  How would that work?

I'm sure I could get answers to this by searching Google but  I'd rather hear from you.