One who uses facebook to convert or attempt to convert others as a proselyte in one's own religious faith or one's own political party, or to espouse one's doctrine.; One who recruits for conversion (a person) from one belief, doctrine, cause, or faith to another.; a royal douchebag; Also, especially British, face⋅book pros⋅e⋅lyt⋅iz⋅er.
verb- "facebook proselytize"
Facebook Proselytizer- (status in news feed on Tuesday) "Ye must be born again!"
Facebook Proselytizer- (status in news feed on Wednesday) "The governor is a scumbag for blah blah blah"
Someone sane on the facebook proselytizer's friend list- "Man, what a douche!?!? Let's see... where's that person... Ah hah! There they are." *clicks the x to remove the facebook proselytizer from friend list* "That's much better."