This is the one-off 1997 Comic Relief special episode, featuring a cross-over story with the other fictional religious BBC series that was also on in the 1990s called "Ballykissangel". This puts The Vicar of Dibley and Ballykissangel within the same fictional universe.
Although never officially re-broadcast as part of The Vicar of Dibley, or Ballykissangel, it is possible to find this episode online on certain video streaming websites.