Christianity

Christanity is the religon in which Jesus Christ/God is worshipped, and is the most common religon in the U.K. Its followers are called Christians. Its holy book is The Bible

Though it is never stated, it is assumed that it is practiced by some in the wizarding world. Things that lead to this assumption are:
 * Harry Potter was christened, which is a Christian practice.
 * Many wizards and witches, such as Lily and James Potter were buried in the Parish Church of St. Clementine graveyard. Most churches do not allow people who were not members of their church to be buried in their cemetery.
 * Albus Dumbledore owns a copy of the Christian bible.
 * Christmas is celebrated in the Wizarding World, which is a christian holiday.