Christianity

Christianity is the religion in which Jesus of Nazareth/God is worshipped, and is the most common religion in the U.K. Its followers are called Christians. Its holy book is The Bible.

Christianity in Harry Potter
Though it is never stated in the books, it has been stated by J. K. Rowling that some wizards do practice Christianity. James and Lily Potter had bible verses written on their tomb stone, so it is known that they did practice, or at least have some belief in Christanity, as they also had a Christening of Harry Potter, their son.

J. K. Rowling has also stated that her stories were based on Christian ideas, thus we assume many characters were Christians as well.

Possible Christians in Harry Potter

 * Harry Potter was christened.
 * Sirius Black was Harry Potter's godfather. In the Church of England, godparents should have been baptized and confirmed before their godchild's christening.
 * Many wizards and witches, such as Lily and James Potter were buried in the Parish Church of St. Clementine graveyard in Godric's Hollow. Most churches do not allow people who were not members of their church to be buried in their cemetery.
 * The Fat Friar was, most likely, a Roman Catholic friar during his lifetime.
 * Albus Dumbledore owns a copy of the Christian Bible.
 * Isobel Ross, a witch, married Robert McGonagall a Muggle Presbyterian minister, who presumably raised his magic children in that religion.

Appearances

 * Harry Potter and the Prisoner of Azkaban
 * Harry Potter and the Prisoner of Azkaban (film)
 * Harry Potter and the Prisoner of Azkaban (video game)
 * Harry Potter and the Goblet of Fire
 * Harry Potter and the Order of the Phoenix
 * Harry Potter and the Order of the Phoenix (film)
 * Harry Potter and the Order of the Phoenix (video game)
 * Harry Potter and the Half-Blood Prince
 * Harry Potter and the Deathly Hallows
 * Harry Potter and the Deathly Hallows, Part 1 
 * LEGO Harry Potter: Years 1-4