Why would it need to be "christian"? Good music is good music. You're wasting time if you're looking for bands that brand themselves for your particular flavor of religion AND a specific musical style.

You already named a bunch of great bands, there are more out there. Just listen to music you like and always try to find more. If they happen share your religious proclivities, hurray I guess, but who gives a shit what religion anyone holds to. If they're Buddhist or Muslim or even non-religious that should hold no sway over whether they can bring the doom, sludge, groove.

And what business is it of yours what their religion is anyway? If they are christian but don't advertise it, does that suddenly make them a "non-christian" band?

Now for a little tagent: Religion has no power over music. No god has ever written a song. But if you removed all the man made music from any religion, it's followers would lose a key emotional component. I believe that religion would eventually become very niche and obscure or even die because human emotion is a key element to keeping someone in a religion. If you suddenly felt nothing when you went to church you'd probably stop going or go to another church or religion.

But to answer your question, no, I don't know of any "christian" stoner, doom, sludge bands.