To paint the bloom of Paradise with the same brush that has depicted the flames and blackness of the nether world; to make the Enemy of Mankind, while preserving this character, an heroic figure, not without claims on sympathy and admiration; to lend fit speech to the father and mother of humanity, to angels and archangels, and even Deity itself;--these achievements required a Michael Angelo shorn of his strength in every other province of art, that all might be concentrated in song.
It is easy to represent "Paradise Lost" as obsolete by pointing out that its demonology and angelology have for us become mere mythology.

This criticism is more formidable in appearance than in reality.

The vital question for the poet is his own belief, not the belief of his readers.
If the Iliad has survived not merely the decay of faith in the Olympian divinities, but the criticism which has pulverized Achilles as a historical personage, "Paradise Lost" need not be much affected by general disbelief in the personality of Satan, and universal disbelief in that of Gabriel, Raphael, and Uriel.

A far more vulnerable point is the failure of the purpose so ostentatiously proclaimed, "To justify the ways of God to men." This problem was absolutely insoluble on Milton's data, except by denying the divine foreknowledge, a course not open to him.

The conduct of the Deity who allows his adversary to ruin his innocent creature from the purely malignant motive "That with reiterated crimes he might Heap on himself damnation," without further interposition than a warning which he foresees will be fruitless, implies a grievous deficiency either in wisdom or in goodness, or at best falsifies the declaration: "Necessity and chance Approach me not, and what I will is fate." The like flaw runs through the entire poem, where Satan alone is resolute and rational.