V in the Index stands for Religion. It includes tales and motifs that have to do with worship and sacrifices, sins, prayers, funerals, religious festivals, saints, angels, etc., as well as some fairly familiar people: "V211. - Christ," "V250. - The Virgin Mary," and "V294. - The Pope." On a more supernatural note, there is also:
V49.1. Werewolves hold mass
Which is a legend from Gascogne in France.
According to Gascon belief, even though they don't have souls, wolves hold midnight mass every year on New Year's Eve (the night before the feast of St. Sylvester). The mass is performed by a Priest Wolf; there are also Bishop Wolves, Archbishop Wolves, and even a Pope Wolf, allegedly, but no one talks much about them.
Legend says that once there was a wheelwright, who moved away from his home town of Mauvezin when he got married. One year, seven days before the feast of St. Sylvester, a messenger came to him, bringing news that his father was gravely ill. Being too far away to travel fast, the wheelwright went to a seer and asked for help. The seer told him that the only thing that could cure his father was eating the tail of a Priest Wolf - hair, skin, bones, marrow, and all.
In order to acquire the tail, the wheelwright agreed to be turned into a wolf. He spent a week with the other wolves, roaming the woods, killing sheep, and doing other wolf things. On the night of the new year, they all gathered in the woods for the mass. The Priest Wolf was in need of a helper, so the wheelwright-turned-wolf volunteered, and helped him perform the mass from start to finish.
After the mass, the wheelwright stayed behind to help the Priest Wolf undress - and as he did, he bit off its tail and ran away back home. When he got to the seer, he was changed back to a man... except he still had wolf ears (and he was still holding the bloody tail in his mouth). The seer tore the wolf ears off, and a pair of "Christian ears" grew in their place.
I am not entirely sure why Thompson tagged this as "werewolves" - the story just calls them wolves, although they are quite sentient. They even have a Pope.
(Find the original text - in French - here.)
Runner-ups
V1.10.1. Man worships a cake which from time to time he eats
V5.2. Negligent priests buried under bags filled with words omitted from service
V5.3. Devils cause monk to perspire and stay away from church service
V30.1.1. Flesh of Artemis eaten as quail or bear
V34.2. Princess sick because toad has swallowed her consecrated wafer
V41.1. Imprisoned miner kept alive by masses performed by his wife
V61.3.0.3. Man buried upright beneath kitchen stairway in order that he may watch his family
V143. Saint’s bones for lack of worship remove themselves from church
V211.1.6. A “crown of thorns” among gifts given by the shepherds to Joseph, husband of Virgin Mary.
V211.1.8.2. Christ in form of an infant fondled by nuns
V224.4. Performing fox accidentally killed miraculously replaced for saint
V229.2.2. Saintly babe disgorges unclean food
V229.2.3.1. Saint as baby refuses to take mother’s breast on Wednesdays and Fridays.
V229.14. Saint in anger shows strength: wall broken by his kick
V261.2. Virgin pardons man who repented for cheating in election
V346. Skeptic kicked by sacrificial animal
V523. The only king ever saved in spite of himself




