ROME — The Eternal City is colliding with the world’s oldest profession — and the sparks, as they say, are flying.

The ranks of streetwalkers have surged here in the heart of Catholicism, a swell that Rome’s officials are decrying as a stain on the dignity of the city’s citizens. But in a town of sinners as well as saints, outright bans on selling sex have failed before, leaving city authorities to put their faith in a new approach.

Their plan is to corral the growing number of sex workers into an unpopulated set of designated streets — in short, a tucked-away red-light district. Proponents reason the working girls can still serve male clients, but beyond the delicate eyes of wives, grandmothers and children.

The “zones of tolerance,” however, are meeting strong resistance from the Catholic Church, the national government and the prostitutes themselves, raising the curtain on a very Italian opera centered on a plan that critics call a classic attempt to sweep “sin” under the rug.