From Tipitina's to the Gospel Tent, spiritual music is not just for church anymore.

Revelry has reached a feverish pitch at Tipitina’s on the eve of Mardi Gras, vibrating the air like a force of nature around the drunk, white crowd waiting to witness the antics of Fred LeBlanc and Cowboy Mouth.

"When I saw the audience, I was concerned," admits Jo Cool Davis, the gospel singer who was about face the horde as the night's opening act. "I mean, Fred...