This is a question that comes up every now and again in social gatherings, and I will now explain my position on the subject.
Many people ask, "If God knows exactly what I will do during life, my life is predestined, right?"
No. "So how does that work then?"
I'm glad you asked. You see God the eternal now. Our timeline starts at one point and ends at another point, but God's timeline doesn't exist. God is now, He was now, he will be now. God simply is.
"But since God know exactly what you will in the next instant, isn't that predestining me?"
No. Everything you do is a choice. Like a monstrous "Y" chart every choice you choose changes your direction. God knows every choice you have: from holding your next breath, to driving off the bridge. Big or small, he knows everything.
So how does that not "predefine" you? Well, God know every choice you have made, have the possibility of making and will make. But He simply knows every ending because He is now.
I heard a minster once say that when Adam and Eve ate the forbidden fruit, God was shocked, and that He then had to figure out what to do to remedy the situation. That is such a small view of God, thinking He was surprised at anything. God is so far beyond our small imaginations that we cannot comprehend His greatness. I think He created humans for more than eternity with Him. I think He created us so He could be like a parent watching His child growing up; enjoying the surprises and relishing the experience with us.
God knows all, but lets us make the decisions for ourselves, rejoicing in our good choices and feeling our hurts when we screw up.