From Fred Phelps' official Westboro Baptist Church site, his church's case for making the trek to SDCC:
Are you kidding?! If these people would spend even some of the energy that they spend on these comic books, reading the Bible, well no high hopes here. They have turned comic book characters into idols, and worship them they do! Isaiah 2:8 Their land also is full of idols; they worship the work of their own hands, that which their own fingers have made: 9 And the mean man boweth down, and the great man humbleth himself: therefore forgive them not. It is time to put away the silly vanities and turn to God like you mean it. The destruction of this nation is imminent - so start calling on Batman and Superman now, see if they can pull you from the mess that you have created with all your silly idolatry.
http://www.comicsalliance.com/2010/07/09/fred-phelps-westboro-baptist-church-headed-to-comic-con/