The great Romantic poet, William Blake, is known for his revolutionary ideas and his fiery attacks on everything he opposed. His work is usually not very complex in nature but since it is connected with the infinite and discusses some imaginary elements, one needs to read his poems more than once to make sense of them. This is exactly what is required when reading Blake's Milton, a poem that respectfully yet firmly attacks Miltonic Christianity of submission and service. It is important to read this poem in the light of Milton's actual philosophies and theology for only then can we understand what Blake was trying to say in his "visionary" poem Milton.
John Milton staunch Puritan and a supporter of the England Parliament firmly believed in serving the God but his images of the Creator and Satan have often come under severe criticism because of the beliefs on which they were based. Milton's religious teachings were considered highly orthodox in nature even though many praised the sublime quality of his poetry. "Sublimity is the general and prevailing quality in this poem [where] the sentiments [ideas], based as they are on scripture, breathe "sanctity of thought." (Johnson, 1779). But that praise apart, Milton's theological views often appear to be contradictory in nature. His image of Satan has also been a subject of heated debate in literary circles for centuries.
Milton would frequently give biblical references in his work, which proved that the poet wanted to adhere to orthodox Christianity, but his views later became quite unacceptable when critics demanded a change in Miltonic version of Christianity. For example Richard Bentlety edited Paradise Lost in 1732 and altered some passages to make them more acceptable, the last two lines of the poem were thus changed to "Then hand in hand with social steps their way Through Eden took, with Heav'nly comfort cheer'd." This is a more positive version of Paradise lost's ending that the one Milton has given us. The audience of eighteenth century wanted to believe in a God who was kind and loving, instead of the one that Milton created in his works.
William Blake tried to speak against this kind of unyielding religious beliefs by highlighting the flaws in Milton's views in his major work Milton. He firmly believed that God in Milton wasn't presented in his true colors because being the sole Creator; He couldn't possibly be as ruthless and unloving as Milton had made him out to be.
For when Los joind me he took me in his firy whirlwind
My Vegetated portion was hurried from Lambeths shades
He set me down in Felphams Vale & prepard a beautiful
Cottage for me that in three years I might write all these Visions
To display Natures cruel holiness: the deceits of Natural
Religion -- Milton 36:21-5
Friedlander (1973) writes: "The living John Milton, Blake tells us, had held wrong views which had contaminated his work. Although he went to heaven after he died, the poet was unhappy because his "emanation," all the things he had produced and loved in life, was spreading error in the world he had left behind. The God of Paradise Lost was remote, cold, cruel, and arbitrary. Milton's poem had made readers think wrongly of God. John Milton had been considering an attempt to salvage his errors. He made his decision after hearing the story of Satan and Palamabron (Hayley and Blake) in a song, which celebrated the inadequacies of conventional morality. As he began his descent, he was encouraged by perceptions of another, ideal Milton."
This ideal Milton is what Blake's Milton is all about. The transformation that occurs in Milton in this poem makes him a starkly different man from the real John Milton because the latter was a staunch Puritan while the former appears to oppose his own views. Most of Milton's poems were rather gloomy in nature with little or no positive messages. His religious teachings and his blindness affected his moods and eventually his work. For example A.S.P. Woodhouse has this to say about Milton's Samson Agonistes:
do not believe that the poem was the product or reflection of a normal mood, but rather of a state of depression not very difficult to imagine in the poet whose world had collapsed around him and who was blind, disillusioned, ill, and essentially alone.
Such must have been the prevailing mood of  1660-1, when the poem, I suggest, was most probably written."
Blake's envisioned a better version of the dead poet, someone who did not support the gloomy version of Christianity. The poem focuses on discarding and dismissing everything that original Milton stood for including his concepts of sublimity and his strict adherence to biblical stories. Blake appears to believe that an ideal Milton would be one who would take into account the limitations of human mind and thus present a more acceptable image of heavenly beings and biblical figures. Blake, in his poem, tries to demystify the image of God by focusing on the attributes, which human beings could relate to. For this reason, he found scriptures a rather unreliable source for illustrating a true picture of God. "In the scripture, whenever God is represented as appearing or speaking, everything terrible in nature is called up to heighten the awe and solemnity of the divine presence. The psalms and prophetical books are crowded with instances of this kind." (Burke, 63)
Another highly interesting transformation that we detect is available in the form of Satan in this poem. We notice that Blake's idea Milton was not an enemy of Satan but rather an ally because both seem to be traveling in the same both. Critics are of the view that Milton was indirectly supporting Satan and sympathizing with him when he presented man as a banished victim in Paradise Lost. Therefore Blake took this view into consideration and showed Milton as an ally of Satan initially thus confirming the critics' views. It is only later in the poem that we see him fighting the evil forces and create a more humane image of God.
Thorp explains: "The nineteenth-century interest, beginning with Blake and Shelley, tended more toward crystallizing in Satan's character the impact of the poem or even toward commending the moral and ethical codes that he represented. The force of the Satanists' beliefs (as they developed during the later nineteenth century) is really an attack (sometimes unconscious) on the underlying ideas of Paradise Lost -- an attack that obliquely condemns the poem for enshrining false and pernicious theological, moral, and ethical notions" (Thorp, p. 9).
Once Milton realizes his mistake of supporting Satan, he tries to atone for it by creating a more positive image of God. This image was more in tune with common religious beliefs and Satan was shunned as the evil force that Milton has mistakenly sympathized with in his works. We must understand that Blake was not against Christianity or scriptures, but he believed that Milton's interpretation of religion was in error and showed Satan as a victim instead of an evil being. Blake along with other critics had been able to detect this strange feature of Milton's theology and thus tried to correct it in his own poem. Thus the Milton that we come across in Blake's poem is first presented as a person with flawed views who later realizes his blunder. The following lines convey the essence of this poem, its objectives and Milton's transformation:
Father most beloved! O. merciful Parent!
Pitying and permitting evil, tho strong & mighty to destroy.
Whence is this Shadow terrible? wherefore dost thou refuse
To throw him into the Furnaces! knowest thou now that he
Will unchain Orc? & let loose Satan, Og, Sihon & Anak