The Christian theologians, including Calvin as well as Augustine and Aquinas, recognize the difficulty of reconciling providence and free will. The truth must live somewhere between two heresies. If it is heresy to deny God's omnipotence and omniscience, then nothing remains outside the all-encompassing scope of divine providence, nothing happens contrary to the divine will, no future contingency is or can be unforeseen by God. If, on the other hand, to deny that man sins freely means that God must be responsible for the evil that man does, then it is heresy to deny free will, for that imputes evil to God.
-Mortimer J. Adler, as excepted from the chapter Fate in The Great Ideas: A Lexicon of Western Thought