Wanted to make sure that I posted this today. I had the pleasure of hearing Mary Karr read in person a couple of years back, and I highly recommend attending one of her readings if ever you have the chance. She's funny, sarcastic, and completely self-deprecating--everything a poet's not supposed to be!
In the podcast linked below, she's pretty blunt about her faith. I love her take on the Eucharist at the end of the first poem.
A Poet in Hell's Kitchen: Mary Karr on "Poetry Off the Shelf"