If someday a history is written of Patty Griffin’s recordings, 2007’s Children Running Through will no doubt stand as a milestone: The Austin songstress discovered she could really thrill her audiences by letting loose. It was that album combined with another, a session with her idol Mavis Staples, that convinced Griffin to record gospel tunes. Downtown Church (Credential) was produced by Nashville Svengali Buddy Miller, who put Griffin at the pulpit in a Civil War–era Presbyterian church and let her go. He rounded up a few of his bandmates from the Alison Krauss/Robert Plant Raising Sand album, and as a result, Church has a similar rootsy vibe. Griffin leans toward the folkie end of gospel, though her song selection is diverse. A couple of original duets seem out of place, as does her take on “Virgen de Guadalupe” (though, oddly, Big Mama Thornton’s decidedly secular “I Smell a Rat” fits right in). But mostly it’s just Griffin and her remarkable voice digging into great numbers by everyone from Dorothy Love Coates to Hank Williams. She’s having a blast, and as time has proved, when Griffin has fun, so will you.