I don't see why the two are incompatible. Except for a few aging fundamentalists and the new born again crop, I think most people who believe in Christianity are able to blend the two. I know most Catholics are like that now, the Vatican, for all its secrecy and scandal has been better than most religions at incorporating scientific fact into its teachings. For instance, most Catholic priests will tell you that dinosaurs were real, and that the big bang and all associated astrological phenomenon is supported by science. So...at least as far as I know, an the way I was raised, the two are quite compatible.
Now I do understand that there are a lot of people out there who use religion the wrong way, and I think that's what BM is trying to get at. SOmetimes the message gets confused and it comes out as Anti-semitic, anti-Christian hate music. If that's the way they choose to present their message than they are preaching a message that is no better than Hitler's. I am not inclined to support either the religious or the anti-religious message but I find the two extremes in both camps to be quite similar to each other. For instance,
Fundamentlist christians and muslims believe that you are condemned to hell, or its equivalent, if you don't believe in what they believe. So basically non-Christian/muslim = bad.
Fanaical satanists and ignorant anti-religious folk use the same type of exclusionary tactics to imply the stupidity or worthlessness of the other group. So, basically Christian/muslim/relgious = bad.
Seems like both sides should just fuck off and let the other believ what it wants. It's not like BM people make the world worse for Christians, or vice versa. Both sides at least to me, are blinded by ignorance and hatred, and I don't think that's what either was intended for. Although, the BM movement from what I understand began because select group of Norwegian metal heads felt that Christianity had suppressed Norwegian culture. If that was the intended message, then it seems that all non-Norwegian BM bands are in it just for the aesthetic and misguided hatred. Although I find the Norwegian position unconvincing, I think that other national groups using the same message as their motivation to be even less convincing.
Live and let live, that's what I say. It's not hard to impiment either. You do your sit and as long as you don't interfere with mine we're cool. Seems quite simple.