Firstly, clicking on the Baa heads in order is an Easter Egg (appropriate for this time!), because the dialogue is from Star Wars before the assault on the Death Star ("Red One here!" "Red Two ready" etc).Secondly, clicking the heads in order "activates" the main Baa head in the large room with all the clerics - when clicked (after clicking head #1-4 in order), it will give you experience. It will also decrease your reputation, so manage this with your Light promotion in mind.
Note that some other guides seem to say that the main Baa head is activated instead by travelling the long winding circular corridor with all the Sparks traps. I've never found this (although I do seem to remember that traversing that corridor does do *SOMETHING*, which for the life of me I can't remember now)
