Milton was a staunch believer in Liberty, from his opposition to the restoration of the Stuart monarchy, to his championing of the doctrine of free will rather than Calvinist predestination.
In Paradise Lost, Milton sets out to 'justify the ways of God to men.' The doctrine of free will is central to his theodicy. Many readers, from the Romantics onwards, have noted that his Satan has 'heroic' qualities, and that our insights into his mind as he rebels against the 'tyrant' God evoke a complex response, which includes sympathy. Milton's God, by contrast, can seem remote, terrible and self-justifying.
So, does Milton's theodicy fail? Not if we're alert to what Milton is doing. We can be swept along and influenced by Satan's rhetoric in his speeches, but Milton's narrative pulls us back, exposing the hollowness, deception and despair of Satan.
When Satan tempts Eve to fall, he does so by appealing to her aspirations to a kind of heroism- he makes fall seem like ascent. Having eaten the apple, she ponders for a while keeping it secret for Adam, relishing the power (delusory) she feels she has over him.
So, in Paradise Lost, Milton explores situations in which characters rebel or act against something they perceive as tyranny, but is not. Their motives may be love of power and evil (Satan), or misguidedness and fallibility (Eve). In Satan's manipulativeness, he provides a study of the means by which true tyrants retain and abuse their power.