The name Baphomet first appeared in trial transcripts for the Inquisition of the Knights Templar in the early 14th century. It first came into popular English usage in the 19th century during debate and speculation on the reasons for the suppression of the Templars.
Since 1856, the name Baphomet has been associated with a “Sabbatic Goat” image drawn by Eliphas Levi which contains binary elements representing the “sum total of the universe” (e.g. male and female, good and evil, on and off, etc.). On one hand, Lévi’s intention was to symbolize his concept of “the equilibrium of the opposites” that was essential to his magnetistic notion of the Astral Light; on the other hand, the Baphomet represents a heretical tradition that should result in a perfect social order, a notion that can only be understood against Lévi’s socialist background.
It is the socialist background that should alarm the Christians. If it was actually Satanism a case could be made that Christians should be pleased, as its the same pantheon of the Catholics. In other words, to worship Satan is in essence, to worship the Catholic god of evil, and therefore brings you into the Catholic orbit. So the debate can be had.
(Yes, Islam has a Satan as well, but like everything else in Islam its a reformatted version which bears a resemblance to its opposite more often than the name would bring to mind.)
It is the socialist aspect of Baphomet which is an attempt to relativize good and evil till there is a level field for all moral positions and actions which should concern these Christian protestors.