Ethan Shanfeld “The Righteous Gemstones” is jam-packed with comedy, action, music and religion. But the beating heart of the HBO megachurch series is the charmingly bizarre romance between middle child Judy (Edi Patterson) and her sheepish husband BJ (Tim Baltz).Created by Danny McBride, the show — whose seventh episode (of nine) aired on Sunday — offers a gold mine of opportunities for Patterson and Baltz to unravel their strange and hilarious relationship.