Erm... Why is everyone talking to "Anonymous" as if it where an Entity? I am Anonymous, and so are you. And You! And even you!
One could do something and claim to be an "Agent" or "Member" of Anonymous and no one, not even a certain group who acted as "Anonymous" could argue about the concept. Except when you get caught, you're definitely no longer anonymous.
Anonymous is pretty much everyone who is not known. There is this Group who act as anon and they have the "right" to do so, since they are not known and even if they where one can't make a connection to any real Person.
About this Website, i'd hack it, place the same document there with some Changes in which i'd add some Counterpoints at the bottom in which i'd criticize this Church for insulting and attacking People.
I wouldn't take over this site and link it to gay porn, the WBC has the right to give everyone a piece of their mind like everyone else does.
However, in hacking this website and adding something i'd exercise my own right to free speech.
I would keep this open letter intact and then add that no Christian has the right to bend the Word of the Lord to fit your own needs. Also, you shouldn't take the Lord's Name in vain, like for example by insulting, attacking and trying to provoke a group that has done nothing to you and then claim that there can be no weapon against People who believe in the Lord.
Wether you believe in the oldest of the old People or not, you'd have to agree that the Westboro Church somehow managed to misinterpret the Bible and make it sound even more violent, narrowminded and stupid. Maybe if those People can be persuaded into reading the Bible again they'd shut their Traps for a while.
But maybe that's not such a good Idea, the Bible is pretty much the most disgusting book i've ever read, practically dripping with the Blood of millions of innocent People that have been viciously killed by God.
Oh well.
Maybe someone should hack this site, leave the open letter intact and then add something like: "Christianity has turned some People into Fanatics that wrote this!" And then add a pamphlet for "Godzilla-ism".