Paradise Lost is a glorious literary triumph with a mortifying failure at its center, and that failure is named God. So it has been judged by critics almost from the beginning, anyway—though this may tell us as much about the uses of literary criticism as about the poem. In a work meant to defend and justify God's works to man, Milton's God is, famously, a tyrannical prig. He's at his worst when we first meet him in Book Three: seeing Satan flying toward this world, then newly created, God convenes a great Council in Heaven in order to "clear His own justice and wisdom from all imputation." This defensive posture is unflattering in any powerful figure, and Milton does his God no favors in writing for him a speech that is ungenerous, self-justifying, and coldly implacable.
Man will hearken to [Satan's] glozing lies
And easily transgress the sole command,
Sole pledge of his obedience. So will fall
He and his faithless progeny. Whose fault?
Whose but his own? Ingrate! He had of Me
All he could have.
Yet God's apologia rests on a notion of human freedom that most modern readers will find uncontroversial and indeed self-evident. Adam had of God "all he could have," all he needed to choose righteousness over sin and thus prove his faithfulness: he had moral freedom "sufficient to have stood though free to fall. . . . Freely they stood who stood and fell who fell." Adam's freedom of will—and nobody disputes that he was free—means that he alone is accountable for his actions. It also means that God can plausibly claim both justice and mercy: justly acquitted from Adam's suffering, mercifully willing to work his salvation.
Milton was not the only prophet to take up human liberty as his great theme. The Book of Mormon prophet Lehi also makes moral freedom the centerpiece of his philosophical magnum opus on human nature and destiny in 2 Nephi 2, and it's no coincidence that he does so, like Milton, in the context of the Adam and Eve story: the Eden myth is a palimpsest for working out the particular preoccupations of each successive generation. Some, like human freedom and bondage, are with us always. Lehi's language is remarkably congruent with Milton's, though of course lacking its elegance:
Men are instructed sufficiently that they know good from evil. . . . Men are free according to the flesh; and all things are given them which are expedient unto man. And they are free to choose liberty and eternal life, through the great Mediator of all men, or to choose captivity and death, according to the captivity and power of the devil (2 Nephi 2:27).
Lehi here makes the point that Milton underscores in Areopagitica: "When God gave [Adam] reason he gave him freedom to choose, for reason is but choosing." And Lehi, again like Milton, uses human liberty as the basis of a kind of syllogistic defense of both divine power and divine goodness, the classic conundrum of theodicy: "For there is a God, and he hath created all things, both the heavens and the earth, and all things that in them are, both things to act and things to be acted upon" (2 Nephi 2:14).
Milton's God, in his off-putting way, goes on to explain a second implication of human freedom, beyond a defense of God's justice and mercy, namely to give meaning to human obedience.
Not free, what proof could [humans] have giv'n sincere
Of true allegiance, constant faith or love
Where only what they needs must do appeared,
Not what they would? What praise could they receive?
What pleasure I from such obedience paid
When will and reason (reason also is choice)
Made passive both, had served necessity,
If humans obey God only because they must, they serve only necessity; such obedience is no worship at all. In this line of thought, at least, true obedience represents an active, sincere, rational, and above all free choice between available alternatives. Compromised freedom is compromised obedience, and compromised obedience garners no praise, offers no pleasure. The logic holds, if one can insist on the fundamental moral freedom of the human mind. Milton can, and Milton does.
Living as he did on the cusp of the modern age, Milton's world comprehended some of the political forms of modernity without yet being undergirded by modern ways of knowing. (Indeed, the failure at the center of Milton's political masterwork, the English revolution, may be reflected in the failure at the center of his literary masterwork.) For Milton, faith is above all a matter of "true allegiance," a relational state between God and man. For modern readers, however, inheritors of enlightenment epistemology, faith is instead or also a kind of spiritual knowledge, a set of beliefs or propositions about the nature of the universe. Milton's God is not only the creator and source of all knowledge, he is also the sole criterion that decides what counts as knowledge; to exercise faith in some set of knowledge, then, is to put the cart disastrously before the horse. By contrast, modern readers approach God inescapably imbued with enlightenment ideals of objectivity and empiricism, and the claims of faith must be evaluated by those standards—or must plead special exception. Milton's God can have nothing to say about this kind of faith, though his Satan hints at it.