its essence as propaganda is the first failing of christian metal. it is intentionally created as a political counteraction to the metal community, supplanting its native values with "safe" ones.
as such, it is a desire to control and destroy, not a desire to compete.
surely the christians could have invented their own genre independently.
it's worth noting that only a few metal bands are satanic, but far fewer have any christian belief, and most believe that christianity is an error best kept in our past.
anyone reading european history might agree.
one sees the opposition of the fundamental idea of metal -- not the satan bands, but the basic idea of a vibrant nihilism outside of god, something that accepts the chance brutality of the world -- to the more placid ideas of christianity. and one sees the return, and it comes in the form of bands designed to fit into the genre, to sound the same musically, but to carry the real-world message of their creed. further, they choose to form a community in antiposition to the current metal community, drawing the line of 'secular' and 'christian'. in their cellular mode of processing, they have found an answer to a phenomenon they have found disturbing, and that is proselytization against the threatening ideas through the mouths of pretenders in the genre.
"christian metal" musicians believe they're doing a good thing. they are creating not art but politics, and furthermore politics against the metal community, instead of within it. this is control. this is normalization. this is conformity.