My understanding of scripture is that they are both true. God does predestine things, but at the same time we do have free will and are therefore culpable for our actions. And if anyone says that is impossible, I can only answer that for Man that is so, but for God all things are possible.
But I take your point that just pointing to scripture is only going to have an effect on a sub-section of the population.
Most of these arguments revolve around placing aspects of God's nature in opposition to one another. Thus, "how can we as mere Humans have Free Will to make independent decisions, in the light of God creating us and knowing all about what we are and what we do and what we will do". It's akin to questions like "Could God ever create a universe so large that even He could not encompass it", which pits God's omnipotence against his omnipresence. The answer is that such an attempt would involve a contradiction of the very being of God, which is impossible. In simple terms God could create a universe so large that even He could not encompass it (because God can do anything), but He knows better than to do it! One of His other attributes, after all, is omniscience!
So, to our original question. God does allow us to make our own decisions, but His knowledge and control of the universe is so complete that it can encompass even the zillions of possible futures that creates. This is not something that any Human Being can ever fully grasp, because as has been pointed out, our perception of the universe is limited by our perception of space and time, which God exists out of. But even this makes sense. After all if God is truly God, and all knowing, all powerful, and so on, is it logical that our Human minds would be able to understand Him? The suspicion arises that a God that could be fully understood by the mind of Man is most likely a product of the mind of Man.