Alfred Henry Lewis 
The Mormon Menace: The Confessions of John Doyle Lee, Danite [EPUB ebook] 

Alfred Henry Lewis was a Chicago journalist in the late 19th century and early 20th century, and though he would become an editor of the local paper, he’s perhaps best known today for the Western novels he wrote.

This is an anti-Mormon screed that Lewis wrote in the early 20th century that depicts the religion from the eyes of a former adherent who left the church.