Have you heard different world by Iron maiden? It has an awesome message of peace. Click here for the song
that's what a lot of people don't relize about metal, the goals are a lot a like(for the most part,once you get to grindcaore and such...eh) but they just don't want to be nice about it. Even slayer with their graphic lyrics are about pro-peace. They just describe what the violence of non-peace really is.
Excactly, If you listen to system of a down, their lyrics are really pro peace. BYOB is a very good example. Iron maiden has made a couple of songs discribing the horrors of war, like paschendale and the trooper.
don't forget aces high. That's just the one thing that pisses me off about people. They think all metal is about hate, it is'nt. They expose the hate in the world. It may be burtal and violant but the for the most part(as I said before there are exceptions) they have the pro-peace and happy for everyone thing. They just don't have a flowers mentalilty for it.