In more traditional, polytheistic belief systems, The "Knower" or "seer" and the "wrter" are two different frces or beings. The weavers of fate rite the fate of the gods as well as men. Fate is generally thought of as having some ultimates, but aso being mutable. Essentially, there are certain fixed points, but free will still exists, as the means by which those points are reached is dictated byt the events and actions of the person in question. There are also stories of those who even managed to change their fate alltogether.
In more modern understandings, the "fixed points" of fate will be reached, but they will do so by following the path of least resistance. If someone's fate is to die at the age of 24, and they are prone to drinking and driving, it's more likely their fate will lead to death in a car crash due to drunk driving than, say, being struck by lightning.
Essentially, you only run into this free will problem when your religion assumes an omnipotent and omnisciesent deity.
Free will runs into lots of problems without needing a deity.
You are just a product of your past experiences, which were a product of events that happened before them, and so on and so on. You have no other choice but to be a member of this forum based on the deterministic continuum you (and all of us) belong to. Maybe you joined this forum to get advice, and you needed advice because you started to grow, and you started to grow because you smoke weed, and you smoke weed because of the friends you have, and you have those specific friends because that's where you were born and environmental factors led you to become friends with them. You're friends with them because your parents moved/live there, and you exist because your parents had sex.
La Place's "demon" says that if you could, at the time of the big bang, know all laws in physics, and you knew where all the matter in the universe is, and exactly how it would react - you could know exactly what would happen at every instant in existence. You would know how/when stars and planets would form, when the first bits of primordial soup gave "birth" to life on earth. You could tell what people were thinking because you would know exactly how every atom would react with every other atom in their bodies, and how external factors would react with those atoms.
Think about every decision/action you make, then think about whether or not you would make the same decision/action under the exact same circumstances. You would, because you wouldn't have any other choice.
Let's say you go to the store and buy a coke;
Why did you buy the coke? Because of ads? The Flavour? Limited Selection of flavours? The reason doesn't matter specifically, just that it was the causal reaction that created the desire for coke.
Now, think about this;
If time somehow rewound itself to before you bought the coke, and you nor anyone else had prior knowledge to going backwards in time, would you chose the coke again - or would you decide something else? I dare say you would chose the coke because all of the factors and variables leading to your decision would be identical. Was it a "choice" to pick coke, or was it external and internal stimuli that you have no control over that lead you to pick coke?
That's "free will"; there is only one possible outcome to any decision you make, the one you made!
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