Good arguments about free will and omniscience building.
When God "tested" Abraham, did he know for sure what Abraham would do?(Assuming, of course, that there was an Abraham, or God).
How about Genesis 15? God allegedly put Abraham to sleep and pointed out: "Know of a surety that thy seed shall be a stranger in a land that is not their's, and shall serve them. And they shall afflict them four hundred years".
This was a guarantee of something that would happen to Abraham's children BEFORE Isaac was even born. assuming the story was true, therefore, we are forced to logically conclude that it would occur as prophesied regardless of what choice Abraham made regarding the sacrifice of Isaac on the alter.
Of course you can argue that "God is this, God is that, or god is the other..." but the fact given is this: Abraham's descendants were to be enslaved four hundred years. Of course, this assumes that any of it ever happened, but if you're going to argue "God" from a biblical perspective, you're sort of stuck with what you're given.
Of course, we can take it as a lesson similar to conclusions of Talmudic scholars: God was showing Abraham that sacrifice would not be the way of obedience or "proof testing" of faithfulness. In fact, the chief "sin" or blasphemy against God is the sacrifice of children at "Tophet", which is to be a great place of burning.
Now, you can argue on this a million different ways, but from what we read above, we would have to conclude that whether Abraham sacrificed Isaac or not, Abraham's descendants would be slaves in Israel four hundred years.
And while we're arguing it, does God create evil? How about Isaiah 45:7? Or Amos 3:6?
Does "free will" mean freedom from God's foreknowledge? From every definition available, from a purely physical view, "free will" is simply the ability to choose as we believe. There is no evidence for anything greater. Freedom is the absence of absolute knowledge.
If you want to try and define God, you will end up exactly with the situation we see today: over 38,000 estimated versions of christianity, none of which can prove the authority of their beliefs, and therefore, as Jesus said in Matthew 24;23, no reason to follow any of them.