"The Chimney Sweeper" is one Big Fat Bummer. It's just chock full of misery. The speaker sees the child crying "'weep! 'weep!" in notes of woe," and then he tells the speaker that he learned those notes from his parents, of all people. In the poem's final stanza, the sweeper blames the church, a priest, and a king as well, claiming they make a "heaven" out of his "misery." Everybody seems to be responsible for making the child unhappy, or for ignoring his feelings, and the kid seems to have no say in any of it, which is the biggest bummer of all.
This speaker just doesn't get it. He's right there with the parents and society, thinking that this kid is totally content. And that means he's also to blame for this kid's misery.
The poem argues that sadness isn't always our fault; the chimney sweeper is "taught" the "notes of woe" by his parents, after all, who also force him to work in chimneys.