William Blake was a profoundly religious man, although his beliefs were somewhat unorthodox by the standards of his time. He was often sharply critical of the Enlightenment, which he saw as disenchanting the world, replacing traditional religious understanding with a cold, logical worldview based on the notion of the planet as a gigantic machine.

At the same time, Blake also rejected formal religion, seeing Christianity as a distortion of man's spiritual life. Blake's main criticism of Christianity was that it turned spirituality into a system of rigid moral laws that were used to keep people in a state of guilt, shame, and oppression. On Blake's account, Christian morality was heteronomous—that is to say, it involved the imposition of standards from the outside, through authority figures such as popes, kings, bishops, and priests. For Blake, this was not just an attack on individual liberty; it also represented a distortion of what true spirituality entailed.

It's not surprising, then, that Blake rejected the rather forbidding, at times tyrannical God of the Old Testament. Instead, he emphasized the presence of the Holy Spirit within the soul of each individual. In common with other Dissenters, Blake believed that religion was an inward affair, a personal relationship between the individual believer and God. Moreover, he did not accept the orthodox Christian belief that Christ died on the cross as a sacrifice for man's sinfulness. To Blake, this was simply another example of human beings projecting their own feelings onto an image of God that they themselves had created. And they proceeded to imbue that man-made image of the Almighty with recognizably human qualities such as wrath, jealousy, and possessiveness. Blake's critical attitude to the traditional Judeo-Christian God is expressed most clearly in his poem "To Nobodaddy," in which he characterizes God as the "Father of Jealousy."