Can't support anyone who supports the WBC. There are people who are in religions for a plethora of reasons; security, conformity, nurture, or just a personal spiritual epiphany. Your friend sounds like he's taking the WBC's side to conform, and find brotherhood amongst those who he thinks share his views and opinions.
This is the type of religious person who sounds devout, but aren't, and on a lower level they just want to fit in, and they've drawn religion out of the deck of cards.
Personally, if someone is "just religious" you should argue with them how you would argue with anyone else. Otherwise you're patronizing or discriminating them based on their beliefs.
It's plain to see most people are firmly against Christian religion's prosthetizing, and I understand, I think that this is invasive and bothersome. I think there's a lot of things this group could do to improve themselves, but keep in mind many religious people are every day people.
I'm a pantheist. I don't use God as an excuse for creation, or divine right, or even for my security. At my root, I just believe there's an essence out there, some sort of embodiment of universal existence in a form, outside of the physical. This means that my views may be more lenient and open to scientific fact and the matter, and there are those religious people that are so rooted in their beliefs they would deny that which is for that which they think is.
But the fact that it exists to them means it exists, in that form.
But, your friend needs to come to understand himself before he can truly understand what he believes.
EDIT: I think it's worth stating that your friend would probably be as thickly routed in his views if they were atheistic views. Religion doesn't so much cause extremism or over zealousness, but because of the variety of interpretations of things like scriptures, it may be more welcome for such people than the straight-forward scientific.
If the person fighting Anonymous was an overtly-ignorant atheist group, not the WBC, and were telling Anon that they were scientifically doomed, and less evolved, etc., and your friend was an extremist atheist, he would still be as he was. His persona comes more from his character than his views.