The criminal duo were caught in the act on Saturday as they tried to rob one of their ten or so known victims, who were all retired priests and nuns, RTL radio reported.
According to a judicial source, the couple obtained their home addresses from a directory listing the clergy members in the Var department of southern France.
The Italian, aged 22, would pretend that he wanted to make a donation before robbing the victims who'd taken out their wallets to receive the gift, the source said.
The couple, who were taken into custody after questioning on the weekend, now face charges of gang robbery.
During questioning they were also found to be carrying several thousands of euros in cash.
Around ten such robberies have been reported in Var over a period of several weeks and 15 outside the department, RTL said.