Marilyn Manson, also known as Marlin Mason, Charlyn Manson, Marlyin Munzon and Marylin Mason, was a goff band. In My Immortal, this band was mainly popular from the mid to late 1980's. In the 1980's, the band XBlakXTearX played on-stage with Marilyn Manson at a concert in Hogsmeade .
In real life, Marilyn Manson's singing career began a decade later. The song he is seen singing in My Immortal is '1996' from his second studio album, 'Antichrist Superstar'. Except the actual lyrics are "Anti people now you've gone too far, here's your Antichrist Superstar", not "jeus christ superstar".