Hail Satan

"Hail Satan", sometimes expressed in a Latinized version as Ave Satanas (or Ave Satana), is an expression used by some Satanists to show their dedication to Satan, but has also been used for the purpose of comedy or satire. Believers in backmasking think they can hear "Hail Satan" and other messages to Satan in some songs played in reverse, such as "Walk This Way" by Aerosmith. The variation Ave Satani, though grammatically incorrect, is sometimes used, likely originating from its use by Jerry Goldsmith in his theme music to The Omen.

Some adherents to a traditional pagan faith (such as the musician Gaahl) have been known to use the phrase to mock Christians or Christianity, using the similarities between Satan as phallic and passionate and pagan fertility-gods such as Freyr in this rhetoric as a disambiguation.

The phrase "Hail Satan" is documented as early as 1808, where it is said in the poem The Monk of Cambray, by an evil monk who uses his pact with Satan to advance in the ranks of the Catholic Church (and finally become Pope). The Latin version Ave Satanas (in its variant spelling Ave Sathanas), often appears in literature at least from the 1800s, notably in the popular 1895 faustian novel The Sorrows of Satan, and earlier in an 1862 play St. Clement's Eve (in reference to satanic undertakings supposed to take place at midnight in a district of Paris). After the phrase "Hail Satan" appeared in the 1967 book Rosemary's Baby by Ira Levin and the 1968 film adaptation of it, where it is said by Satanists when they believe Satan's will has been accomplished, and had also appeared in other films and in stock footage, the phrase became part of the common conception of what Satanists say. Some film actors were reluctant to say it, and of those who did some felt they experienced negative life events afterwards, such as divorce.

...
Wikipedia