On the 29th December 1170, Thomas Becket – the Archbishop of Canterbury – was murdered in front of the altar of Canterbury Cathedral. He had been appointed by Henry II to the most important religious position in England in 1162, but was slain after some of the king’s men interpreted one of their ruler’s angry outbursts as the desire to have Becket killed.

Thomas Becket was appointed Chancellor by Henry in 1155. In this job he proved himself to be a loyal member of the king’s court and so when Theobald, the existing Archbishop of Canterbury died, Henry saw his chance to dominate the church by appointing Becket to succeed him.

Having a loyal friend in the most senior religious position in England made sense to Henry. However, as Archbishop of Canterbury, Becket’s allegiance quickly switched to siding with the church. This frustrated Henry, who asked Becket to sign the Constitutions of Clarendon in 1164 to extend the king’s authority over the clergy. Becket refused, and shortly after being summoned to the king to explain his actions fled to France.

Becket returned in 1170 but, after excommunicating members of the clergy for supporting Henry, found himself the target of an angry outburst by the king – which almost certainly wasn’t  “Who will rid me of this troublesome priest?” Whatever Henry did say, however, it was enough to encourage four knights to travel to Canterbury and kill him inside the Cathedral. It is said that the fatal blow split his skull. Becket was canonised by the Pope barely two years after the murder, and in 1174 the king himself walked barefoot to Canterbury in penance.

On the 27th December 537, Hagia Sophia was inaugurated by Byzantine Emperor Justinian I and Patriarch Menas of Constantinople. The current building is the third church of Holy Wisdom to be built on the site, after the first two were destroyed in separate riots and revolts. However the third church’s long history saw it serve as both a Greek Orthodox cathedral and a Roman Catholic cathedral, before Constantinople was conquered by the Ottoman Turks under Sultan Mehmed II in 1453. He ordered it be converted into a mosque, which it remained until being secularised and reopened as a museum on the 1st February 1935.

The architects of the enormous basilica were the physicist Isidoros of Miletos and mathematician Anthemios of Tralles who, as the first to put together a comprehensive compilation of the mathematical theories of Archimedes, was clearly heavily influenced by the Greek academic. The two architects devised a series of complex vaults and semi-domes surrounding a high central dome with a diameter of over 31 meters. Supported by four marble-clad arches, this dome is probably the most immediately recognisable part of the building although it is not the original structure. The first dome collapsed during an earthquake on the 7th May 558, and was rebuilt over the next four years.

After Mehmed II was victorious in what became known in the west as the Fall of Constantinople in 1453, he ordered the basilica be converted into a mosque. This involved stripping it of Christian iconography but also building the four minarets that surround the central dome and are now a major part of the Istanbul skyline.

The Exorcist is one of the highest-grossing films of all time, but originally opened in just twenty-six American cinemas. Famed for its ground-breaking special effects, the film terrified audiences yet was nominated for ten Academy Awards of which it won two.

The film, directed by William Friedkin who had previously had success with The French Connection, was adapted from William Peter Blatty’s 1971 novel of the same name. This was itself inspired by reports of the real-life exorcism of an anonymous boy known by the pseudonym Roland Doe that emerged in the late 1940s. Blatty described his novel as ‘an apostolic work’ that sought to prove that if supernatural evil existed then so too must supernatural good.

These themes came through in Friedkin’s film, but for many audience members it was the sight of the twelve year-old Regan’s spinning head, levitation, vomiting and other extreme behaviour that proved most shocking and most memorable. With newspapers reporting cases of people fainting at screenings, The Exorcist quickly became a social phenomenon.

The film went on to sell 6 million tickets within just three months of its release in the United States despite a mixed response from the critics. While Variety praised its “expert telling of a supernatural horror story”, the New York Times criticised it as “a chunk of elegant occultist claptrap”.

Such negative responses failed to affect the film’s success, however. The Exorcist was the second most popular film of 1974 and, once gross earnings are adjusted for inflation, remains the ninth highest-grossing film of all time.

On the 27th November 1095, Pope Urban II launched the First Crusade with an impassioned speech at the Council of Clermont. The Byzantine Emperor Alexios I Komnenos had appealed to the Pope for support against invasion by the Seljuk Turks, and many historians argue that Urban II took advantage of the situation as a way to reunite Christendom under the papacy.

By the 11th Century, Christianity had secured a stable base across most of Europe. However the Byzantine Empire was on the very periphery and faced continuous threats from Muslim conquests. The city of Jerusalem had been in Muslim hands since 638, but ongoing wars between different Arab dynasties had resulted in it being captured by the Seljuks in 1076. When their army began threatening to attack Constantinople, Alexios appealed to the Pope for assistance.

There is no record of how many people responded to the Pope’s call, but estimates suggest anywhere between 60,000 and 100,000 of which a large number were ordinary peasants. Exactly why so many people chose to “take the cross” is also a question subject to fierce debate. Certainly some nobles went in the hope of seizing riches along the way, but a large number of crusaders almost certainly did so out of piety.

Although Pope Urban had intended the Crusade to depart on the 15th August 1096, large numbers of peasants and low-ranking knights set off earlier on what became known as the People’s Crusade. Poorly disciplined and with little to no military training, these Crusaders killed thousands of Jews in the pogroms of 1096 before even leaving Europe.

On the 5th November 1605, the Gunpowder Plot was foiled when Guy or Guido Fawkes was discovered guarding 36 barrels of gunpowder that had been placed in an undercroft below the House of Lords in London. The failure of the plot and execution of the conspirators has since been commemorated in Britain on what is known as Guy Fawkes Night or Bonfire Night, where effigies of Guy Fawkes are traditionally burned on a bonfire amidst large firework displays.

The Gunpowder Plot was conceived at a time of significant religious tension in the British Isles. Less than a century had passed since Henry VIII broke from Rome, and Catholics continued to be persecuted when James VI of Scotland was crowned James I of England. Led by Robert Catesby, a group of thirteen Catholics conspired to blow up the House of Lords during the State Opening of England’s Parliament, when James would be inside the building. Having killed the king, they would then initiate a revolt that would bring James’ young daughter Elizabeth to the throne as a puppet queen. However, the plot was revealed in an anonymous letter and the search of the undercroft was conducted late in the evening of the 4th November.

Most people know that Guy Fawkes, along with the other surviving conspirators, was sentenced to execution by being hung, drawn and quartered. However, what is less widely known is that he managed to leap from the gallows and break his neck. Fawkes was therefore already dead by the time the executioner began to carry out the more gruesome parts of his sentence.

On the 4th October 1582, Pope Gregory XIII implemented the Gregorian calendar. Although this calendar is now the most widely used calendar in the world, it was initially only adopted by the Catholic Church and the Papal States since to become a nation’s official calendar it had to be approved by the civil authorities. The only areas to therefore implement it on the specified date were the territories governed by Philip II of Spain, the Polish–Lithuanian Commonwealth, and the Papal States.

Due to a drift between the Julian calendar, the lunar calendar, and the real moon, the date on which the church celebrated Easter had begun to move away from when it had been celebrated by the early church. The Catholic Church disliked this seasonal drift, and so decreed the papal bull Inter gravissimas in early 1582 to reform or – in the words of the Latin text to ‘restore’ – the calendar to align with that at the time of the First Council of Nicaea in 325.

Due to thirteen centuries’ worth of accumulated variations between the existing and new calendars, the change to the Gregorian calendar demanded the deletion of ten days. Consequently, in the territories that adopted the new calendar, the day after the 4th October 1582 became the 15th October – although the day of the week did not change.

Although most Catholic countries swiftly adopted the Gregorian calendar, Protestant governments initially rejected it. However, by the end of the 18th Century most of the countries of Western Europe – including the sizeable British Empire – switched to the Gregorian calendar to ease international trade.

On 2nd October 1187, the Siege of Jerusalem came to an end when Saladin captured the city from the crusaders who had ruled the city since 1099. Having been defeated at the Battle of Hattin on 4 July 1187, the Crusader Kingdom of Jerusalem was left with only its capital city having not been captured by Saladin’s armies. The siege lasted for just twelve days before Jerusalem’s leader, Balian of Ibelin, agreed to surrender the city.

King Guy had been taken prisoner during the Battle of Hattin, leaving Balian as the most senior noble in the Kingdom. Having travelled to Jerusalem to rescue his wife and family, Balian was persuaded to stay and lead the defence of the city although this meant breaking an oath he had sworn to Saladin that he wouldn’t stay in Jerusalem for more than a day.

Arriving at the city on the 20th September, Saladin provided an escort for Balian’s wife and children who were moved to safety in Tripoli. Meanwhile, he began a relentless assault on the city that eventually led to a breach in the wall. Although the attacking army was unable to gain access to the city, the lack of knights available to maintain the city’s defence led Balian to negotiate the surrender. In return for unconditional surrender, Saladin agreed that anyone who paid a ransom would be able to leave the city in safety. He later freed thousands more who were unable to pay, but approximately 15,000 inhabitants were enslaved.

Two years later, the Third Crusade was launched to reconquer the Holy Land from Saladin.

On the 16th September 1978, filming began on Monty Python’s Life of Brian. Seen by some as the greatest comedy film of all time, the film has courted controversy since its release due to its satirical portrayal of religion that is interpreted by some as blasphemous.

Life of Brian was the third motion picture to be released by the Monty Python comedy troupe, and is said to have had its origins in the publicity circuit accompanying their previous film Monty Python and the Holy Grail. The box-office success of Holy Grail had proved that there was significant demand for feature-length creations from the group, and soon the idea of lampooning organised religion became a focus for development.

Two members of Monty Python, Eric Idle and Terry Gilliam, dismissed the idea of a direct satire of Jesus Christ since they agreed that – despite both being non-believers – there was nothing to mock in his teachings. Therefore they settled on the idea of his neighbour, Brian, being mistaken for the Messiah despite not wanting the attention.

It took just over a year for the script to be completed, and EMI Films had been lined up to fund the project. However, just two days before filming was due to begin the funding was withdrawn on direct orders of the company chief executive. Faced with catastrophe Eric Idle confided in his friend, ex-Beatle George Harrison, who stepped in to save the film by providing £3 million through his production company HandMade Films. It grossed over $19 million in America alone during its first year of release.

The Adi Granth, the original holy scripture of Sikhism now known as Guru Granth Sahib, was first installed at the Harmandir Sahib Golden Temple.

Beginning with Guru Nanak, the founder of Sikhism, the gurus had distributed collections of hymns to distant Sikh communities. The Adi Granth was a compilation of these texts assembled by Guru Arjan, the fifth Sikh Guru, who had inherited the role from his father, Guru Ram Das, in 1581.

While collating the work of his predecessor, Guru Arjan realised that some of the legitimate writings had been infiltrated by forged works from other people who sought the guruship. Keen to stop the illegitimate texts from spreading, Guru Arjan set about compiling the writings of Guru Ram Das and the first three gurus into a single volume.

The Adi Granth manuscript was completed in 1604 and it was installed at the Golden Temple, which Guru Arjan had also designed, on 1 September that year. Copies were sent to Sikh communities across northern India while the book remained unchanged until the tenth guru, Guru Gobind Singh, added the writings of his predecessor to it. Guru Gobind Singh later ended the human line of gurus by announcing the text itself as his successor on 20 October 1708. Consequently this second rendition of the Adi Granth became known as Guru Granth Sahib.

Guru Gobind Singh instructed Sikhs to respect the Guru Granth as an embodiment of the ten Gurus who had come before it. Consequently Guru Granth Sahib is considered within Sikhism to be the final Guru, since it contains answers to all questions regarding religion and morality.

On the 18th August 1612, the trials of nine Lancashire women and two men known as the Pendle Witches began. Accused of various murders, twelve people were charged of whom was found not guilty and another died in prison before going to trial. The other ten were found guilty and executed by hanging.

The trials of the Lancashire witches are not only some of the most famous, but also some of the best recorded witch trials in British history. This is due to a published account called The Wonderfull Discoverie of Witches in the Countie of Lancaster by Thomas Potts, the clerk to the Lancaster Assizes where all but one of the trials took place.

One of the most interesting things about the trial is that the majority of the defendants self-identified as witches, or at least as village healers who practised what they referred to as ‘magic’ in return for payment. A number of the accused even admitted to Roger Nowell, the justice of the peace for Pendle and chief prosecutor at the trials, that witchcraft had been practised by a number of people in the area around Pendle Hill for many years.

In historical terms, the Pendle Witch trials were significant for their scale. Despite a popular belief that witch trials were a common occurrence in the early modern period, only around 500 people were executed for witchcraft throughout the 300 year period when they were carried out. This means that the ten found guilty in Pendle represented an astounding 2% of all British witches to face trial during the period.