I voted to keep religion out of my metal. While I respect artists' decisions to speak of God in their lyrics, and tell stories of such, I would never personally buy a CD that will try to preach to me as I listen to music.
Hard metal music, though appropriate at times, was not intended for religious songs. Industrial music (a segment of metal) uses very deep themes, and God is often mentioned... however, the lyrics manage to fit the mood of the song. Actually, it's the song that fits the lyrics.
Christian Metal, I believe, was made to stretch the mighty hand of the "Xtian" music genre and therefor get more listeners... and ultimately more money for the church, which God can always seem to provide when enough zeal is put forth ¦¬Þ. What I'm saying, is that religious lyrics (ones that speak directly of morals and the path to righteousness) don't necessarily demand the beats of metal. Rather, metal is selected as a "canvas" for the lyrics so that it'll sell better.
I don't feel you have to listen to Christian music to show loyalty to your religion. If you feel otherwise, how can Christian Metal feel appealing, when metal is highly... "frowned upon" by many of the strict-religious types? I'm not trying to start too much confusion, really. It's just, do you really listen to the music for the words, or for the beat? If for the words, why not just listen to more fitting music to the message? If for the beat... why not find albums that have much more appropriate lyrics (not necessarily about killing people, heh)
... Oh, I also suggest you check out
Megaherz (translates - Mega Heart). Not quite Christian Metal, but it
does have really interesting themes (check lyrics).
These lyrics, for example. I played that song in English and provided lyrics as part of a project. It freaked people out, wooohg ¦¬Þ