Heavy metal music
Critics disagree over who can be thought of as the first heavy metal band. Most credit either Led Zeppelin or Black Sabbath, with American commentators tending to favour Led Zeppelin and British commentators tending to favour Black Sabbath, though many give equal credit to both. A few commentators—mainly American—argue for other groups including Iron Butterfly, Steppenwolf or Blue Cheer. Deep Purple, the third band in what is sometimes considered the "unholy trinity" of heavy metal (Black Sabbath, Led Zeppelin, and Deep Purple), despite being slightly older than Black Sabbath and Led Zeppelin, fluctuated between many rock styles until late 1969 when they took a heavy metal direction.
Stryper
Stryper is recognized as the first openly Christian heavy metal band to gain recognition in the mainstream music world. Their message of salvation has also made them popular with some elements of the media. Mark Joseph states ""The Yellow and Black Attack" was propelled by the group's success in Japan, which was largely due to an endorsement of the band by famed rock critic Masa Itoh, the man who ruled the Japanese hard rock/metal scene, who many fans looked to for his evaluation of bands. Itoh had heard of Stryper, gotten in touch with their manager Daryn Hinton, and liked what he heard. When he gave the band a positive review in Japan's heavy metal bible "Burrn!" magazine and played the album on his radio show, Stryper suddenly found themselves at the top of the metal heap in Japan with a record that was outselling Mötley Crüe, Bon Jovi, and every other metal band." This led to the band signing with CBS Sony in Japan.