Kravitz takes damage from holy energy, at least in his crystal form, and seems pretty edgy around Merle. Barry was solidly repelled by a holy symbol and even in human form it put him in a bad state. In short, they’re all useless and undead, even if they do work for a goddess. She’s a goddess of dead things, okay? Her realm is a bit iffy and her reapers are breaking the rules by anyone’s standards.
Merle brings out Angelic Della Reese at a BoB barbeque one time without out thinking about it, just to entertain the kids, and Kravitz, Lup, and Barry disappear. They’re gone, across the quad and barricading themselves in Lucretia’s office in a split second flat. Kravitz actually leaves his body behind, Barry and Lup can’t because they’re a little more alive then he is but they do make a solid effort at escaping through the air vents. Merle wises up after that, and stops using big holy shows of force when his undead friends are around. He will break up fights with the XTreme Teen Bible sometimes though. A bop on the head usually has any one of them reeling back.
He finally stops after Lup snaps and pulls a scythe on him, and after that there’s a strict “no weaponized religion at family events” rule. The three of them have to sit a few rows back at Carey and Killian’s wedding, just in case their non-denominational vows get too intense, and Kravitz politely turns down invitations to go to a few potlucks at the Temple of Istus in Refuge, but it’s good, it’s fine. At least it would be if Taako didn’t find their “allergy” absolutely hilarious. He keeps threatening to get a spray bottle of holy water to use on them. Lup keeps threatening to murder him so he’ll know how the whole undead thing feels.