Metal and rock music have long been associated Satanism due to Satanic references and symbols in music, such as the number 666. But a lot of the artists were incorrectly labeled as Satanists because of such references, when in fact, a lot of them were Atheist or practiced Christianity and other religions.
Black Sabbath were one of the first metal acts to be accused of practicing Satanism because of their name and the content of some of their songs. Tony Iommi's use of "the Devil's interval" tritone gave the music a sinister twist, especially in "Black Sabbath." However, the members were all Christians, and songs such as "After Forever" on Master of Reality showcased these beliefs.