That is, free will - capacity of rational agents to choose a course of action from among various alternatives - and Free Will - a 'metaphysical' idea of being responsible for one's actions - are impossible because God knew exactly what one would do for an eternity before He created him.
http://plato.stanford.edu/entries/fatalism/Though the word “fatalism” is commonly used to refer to an attitude of resignation in the face of some future event or events which are thought to be inevitable, philosophers usually use the word to refer to the view that we are powerless to do anything other than what we actually do. This view may be argued for in various ways: by appeal to logical laws and metaphysical necessities; by appeal to the existence and nature of God; by appeal to causal determinism. When argued for in the first way, it is commonly called “Logical fatalism” (or, in some cases, “Metaphysical fatalism”); when argued for in the second way, it is commonly called “Theological fatalism”. When argued for in the third way it is not now commonly referred to as “fatalism” at all, and such arguments will not be discussed here.
The interest in arguments for fatalism lies at least as much in the question of how the conclusion may be avoided as in the question of whether it is true.
http://www.newadvent.org/cathen/06259a.htmThe question of free will, moral liberty, or the liberum arbitrium of the Schoolmen, ranks amongst the three or four most important philosophical problems of all time. It ramifies into ethics, theology, metaphysics, and psychology. The view adopted in response to it will determine a man's position in regard to the most momentous issues that present themselves to the human mind. On the one hand, does man possess genuine moral freedom, power of real choice, true ability to determine the course of his thoughts and volitions, to decide which motives shall prevail within his mind, to modify and mould his own character? Or, on the other, are man's thoughts and volitions, his character and external actions, all merely the inevitable outcome of his circumstances? Are they all inexorably predetermined in every detail along rigid lines by events of the past, over which he himself has had no sort of control? This is the real import of the free-will problem.
As a reduction, Pike asked:
Let us suppose that being omniscient involves being infallible, and believing that p if and only if it is true that p.
Let us also suppose that God existed in 1900, and that omniscience is part of his essence.
Now, suppose that Jones mowed his lawn on 6/1/2012.
Then God believed in 1900 that Jones would mow his lawn on 6/1/2012.
Did Jones have the power to refrain from mowing his lawn?
. 
