During the mid to late 1960s, the large abundance of rock and roll acts emerging forced some of them to diversify in order to carve out niches in the market place to distinguish themselves. The Beatles, Bob Dylan, the Byrds, Cream, James Brown, Miles Davis, and Jimi Hendrix led the way by combining different forms of music to create new forms and trying other experiments. The end result of these combinations and experiments was new hybrids, such as folk rock, country rock, psychedelic rock, art rock, funk, and heavy metal.
Around the same time, some bands, particularly heavy metal bands, started incorporating outrageous shock and other marketing concepts and gimmicks into their personas, stage shows, and music. In addition, they would play off of teenager’s curiosity, fear, and anxiety of the unknown, mysterious, horror, and occult. Some of the musicians who liked to over-indulge with drugs, groupies, orgies, and illegal activities welcomed this because it fit in well with their life styles and they did not have to hide it anymore.
The end result of these forces were heavy metal bands like Black Sabbath, Alice Cooper, and Led Zeppelin. And because these acts were very popular and profitable, heavy metal music got associated with "devil worshipping, evil, and the occult." This is a shame because heavy metal, as a music form by itself, provides such a natural rush. Ultimately, the popularity and profitability of these acts generated a flood of clones in the market which just reinforced this image and perception, such as KISS, Blue Oyster Cult, Nazareth, AC/DC, and Judas Priest. Today's third and fourth generation clones are just regurgitation of the originals, but with more emphasis on pushing shock value.
Many of the gimmicks and antics that these musicians employ are comical and hysterical, much in the same way as "professional wresting." Meanwhile, these musicians are laughing at all the money they profit by playing the more gullible fans for a tune. Yes, there may be some acts and some fans that really believe all the silliness they are spewing. The more power to them.
However, it needs to be recognized and acknowledged that some ideas, concepts, and emotions are negative and can be destructive towards individuals, relationships, families, communities, and society. Although providing escapism, relief, and change of environment, some forms of entertainment clearly undermine the basic foundations of society trying to advance beyond the animal base by acting as negative and destructive influences.
The only comment to those who glorify evil themes in their musical acts is that remember that in terms of overall simplicity, it is evil and all its represented forms that are repressive on the advancement of humanity via hate, crime, murder, greed, etc. At the end of the day, have these musicians contributed toward building a better world? Or have they just made themselves richer?