By definition, God is an all-knowing being. This means that God knows everything, even events that will happen in the future. God knows what choices each and every person will make and He knows all of the outcomes as well. This means that human lives are already predetermined. God knows exactly how our lives will turn out, otherwise he wouldn't be all-knowing. So, if God does exist then free will cannot possibly exist. Every thought, decision, and action is already predetermined and our futures are already fixed.
