I don't get the problem with this whole 'unblack' or 'white' metal thing.
The term 'unblack' is nothing more than a title thought of by Anonymous of Horde, as a wordplay to Darkthrone's unholy black metal. He decided to call his music holy unblack metal. Nothing more or less. The music isn't or ever will be any different. And to say BM and Christian lyrics don't mix seems a bit narrowminded to me. There are so much 'secular' bands out there that also don't sing about satan or so, but about nature, history or mythology, to name a few. And they are well excepted.

Same with the 'white' metal term. This is merely concieved by a clever salesman that wanted to sell the records of the band Trouble. Due to the fact that Venom just put out their black metal album, and the record of Trouble contained possitive lyrics, here called that one a 'white' metal album.