Reply #12: Two words:

[Magrittes Pipe]

Sam Cooke.

Brilliant Gospel singer, brilliant secular singer.

Aretha as well -- she didn't really have a career in Gospel, but that's where she got her start.

I am hard-pressed to think of any post-rock white artists about whom one can say the same, though. Before rock & roll, there were a lot of great artists who crossed-over between sacred and secular music in country and western -- two huge examples being Hank Williams and the Carter Family.

Ah, the Carter Family. That brings me to the one white post-rock performer who made great records in both Gospel and secular music:

Johhny Fucking Cash.