Divine predestination and human action are two different perspectives on the same thing, but you can't really consider them alongside each other on the same plane. It's as if God is an author writing a story. On one level, He determines everything that happens. On another level, the characters in the story are held responsible for their actions within the story.
This isn't, of course, to say that God is totally outside of the story, as an author is. He is perpetually involved, and that's where my analogy breaks down.
