Opposition to anything that oppresses the human spirit dominates Songs of Innocence and Songs of Experience. To what extent do you agree?

Blake wrote at a time when the European and American worlds were being transformed through war and revolution. He was an 18th-century progressive, his circle including the reformers William Godwin, Mary Wollstonecraft, and Thomas Paine, so it is not surprising that in his own writings he empathized with the weak and oppressed.
In Songs of Innocence the poem "The Chimney Sweeper" is a criticism of the exploitation of children on both the societal and individual level: "....my father sold me while yet my tongue / Could scarcely cry 'weep, 'weep, 'weep, 'weep.'" Both the child and the parents are oppressed victims of society: the general conditions of poverty in which the English working class lived have evidently caused the mother's death and the father's need to "sell" the child, now forced to work as a chimney sweep. (In a later time the same thought is expressed in the melancholy song of the Chimney Sweep in Mary Poppins, where he ironically sings that a "chimney sweep's lucky as lucky can be.")
A more subtle and ambiguous example in Songs of Innocence is in "Holy Thursday." Blake's attitude to religion was complex and, by conservative standards, rather heretical. The children in this poem are described in a way that suggests cattle being marched to the slaughter, as they are led by "grey-headed beadles." Blake was anti-clerical and believed in a new, radical form of Christianity, as opposed to that of the Established Church. In Songs of Experience the corresponding "Holy Thursday" poem makes the implied radicalism of the earlier poem explicit, with its reference to "Babes reduced to misery, / Fed with cold and usurous hand." And of course, the same is true of the corresponding Chimney Sweeper poem in the Experience cycle, with the child crying in its "notes of woe," while the mother and father are "gone up to the church to pray," the Church again representing the Establishment which seemingly neglects the poor and oppressed in order to serve the rich.
One can say these are critiques of material, rather than spiritual, oppression, but in Blake the two forms are mirror images of each other. "The Garden of Love," though not as famous as "The Tyger" and several of the other poems, is perhaps the one poem in which Blake's various themes are brought together: "The gates of this Chapel were shut," and "priests in black gowns were walking their rounds / And binding with briars my joys and desires." This is not simply a criticism of the religious system for taking little heed of the poor. It gets to the heart of Blake's view that religion stifles the inner (spiritual) needs of people by essentially teaching that joy and happiness should be denied to them, and that they should feel guilty about experiencing them. And in "The Tyger," the animal itself represents a primal force of nature and desire which cannot be denied, though Blake is ambivalent about it. In the verse "When the stars threw down their spears / And watered heaven with their tears," the suggestion is that God, or heaven, regretted the creation of this force and the negative factors it carries with it. The poem "London," in which the speaker notes the "marks of weakness, marks of woe" throughout the city, is a kind of culmination of Blake's awareness of and sympathy for both the materially and spiritually deprived in society.
Blake's work is replete with contradictions, above all the fact that he was religious but anti-church; these examples overall show that an overriding concern was his sympathy for the weak and dispossessed in the world.