In the Book of Mormon it says “Behold there are save two churches only; the one is the church of the Lamb of God, and the other is the church of the devil; wherefore, whoso belongeth not to the church of the Lamb of God belongeth to that great church, which is the mother of abominations; and she is the whore of all the earth.”
Geez, Mormons are pretty harsh on other churches, eh? Well, there are multiple ways to interpret this. One is to say that the LDS Church is the church of the Lamb of God and every other church is the church of the devil. On the other side of the spectrum you could say that good people are the church of the Lamb of God, and bad people are the church of the devil. In the past, even LDS authorities have speculated and/or stated that the church of the devil was a specific church, but the LDS Church’s stated position today is that the church of the devil is “Every evil and worldly organization on earth that perverts the pure and perfect gospel and fights against the Lamb of God.” This view is supported in the article Warring against the Saints of God by Stephen E. Robinson where he lays out a detailed explanation showing that the church of the devil is not a label that can be applied to any specific denomination.