Literal translation
he is as poor as a church rat
Meaning
he's as poor as a church mouse
Explanation
This comparison marks extreme poverty by evoking the image of a rat living in a church. The word rendered as rat also denotes, by extension, a whim or the jack in the game of bowls, but it is the literal sense that applies here. The word for church could be verified directly. Provençal churches, stripped of food and warm corners unlike a barn or a kitchen, offer a habitat where even a rodent, usually known for eating almost anything, would find very little to feed on. The image thus reverses the rat's usual reputation as an opportunist, well fed everywhere else, turning it into the very symbol of destitution once placed in a resourceless setting. It is used to describe a person with absolutely nothing, in a casual, vivid register, very close in both construction and meaning to the well known French equivalent, which makes it immediately understandable.