Not to be confused with the Inverted Cross, the Satanic Cross is a modified version of the alchemical symbol for sulphur, representing fire and brimstone. It is also theorized to be a combination of the Cross of Lorraine, a symbol carried by the Knights Templar into battle on their banners, and the Infinity Symbol, in such a manner as to represent a phallus. Phallic symbols were used by the pagan ancients as a good luck symbol, a sentiment Anton LaVey adopted in The Satanic Rituals — some of which involve the use of a golden phallus for idolatry purposes.
The symbol was placed above LaVey’s Nine Satanic Statements in publications of the Satanic Bible, cementing its reputation as a Satanic symbol.
Sometimes, as depicted below, the Satanic Cross is combined with the Ouroboros symbol.