Artists don't operate from an 'ideology' in the sense of a coherent and cohesive dogmatic checklist (at least, good artists don't, polemicists masquerading as artists do - most 'politically' oriented hardcore bands, for instance - but that's not art, it's preaching). But there's a consistent worldview and approach to living that emerges implicitly from extreme metal, even if not all the artists excel at articulating that worldview, say, in interviews (though the best, the Tom Fischer/Varg Vikernes/Luc Lemay do well in any arena).