Pope John Paul I conspiracy theories
Pope John Paul I died in September 1978 only a month (just 33 days) after his election. The suddenness of the death, together with the Vatican's difficulties with the ceremonial and legal death procedures (such as issuing a legitimate death certificate), have resulted in several conspiracy theories.
Discrepancies in the Vatican's account of the events surrounding John Paul I's death — its inaccurate statements about who found the body,  what he had been reading, when and where and whether an autopsy could be carried out — produced a number of conspiracy theories, many associated with the Vatican Bank, which owned many shares in Banco Ambrosiano.
Some conspiracy theorists connect the death of John Paul (in September 1978) with the image of the "bishop dressed in white" said to have been seen by Lucia Santos and her cousins Jacinta and Francisco Marto during the visitations of Our Lady of Fátima in 1917. In a letter to a colleague, John Paul had said he was deeply moved by having met Lucia and vowed to perform the Consecration of Russia in accordance with her vision.
There are several populist conspiracy theories that have not been formally turned into manuscripts. Chief among these is one popular with Franciscans in Rome that alleges that the paper found in his hand was a copy of his sermon to be given the next day (he died on a Saturday night, the body was found Sunday morning). In it he allegedly discussed the fact that the Old Testament Yahweh has been universally personified as a father figure, yet there is nothing to prevent an interpretation of Yahweh as a mother figure, a la "earth religions". He then supposedly went on to give several examples of Old Testament events that made much more sense seeing God as Mother rather than Father. The theory also states that a copy of St. John of the Cross' Dark Night of the Soul was open on his bedstand.
David Yallop's book
David Yallop's 1984 book In God's Name proposed the theory that the pope was in "potential danger" because of corruption in the Istituto per le Opere Religiose (IOR, Institute of Religious Works, the Vatican's most powerful financial institution, commonly known as the Vatican Bank), which owned many shares in Banco Ambrosiano. The Vatican Bank lost about a quarter of a billion dollars.
This corruption was real and is known to have involved the bank's head, Paul Marcinkus, along with Roberto Calvi of the Banco Ambrosiano Calvi was a member of P2, an illegal Italian Masonic lodge. Calvi was found dead in London in 1982, after disappearing just before the corruption became public. His death was initially ruled suicide, and a second inquest – ordered by his family – then returned an "open verdict".
Upon publication of his book, Yallop agreed to donate every penny he made from sales to a charity of the Vatican's choice if they agreed to investigate his central claim, that when the body of the pope was discovered, his contorted hand gripped a piece of paper that was later destroyed because it named high-ranking members of the curia who were Freemasons and others who had a role in numerous corruption scandals and the laundering of mafia drug money. One of the names believed to be on the paper was that of bishop Paul Marcinkus, who was later promoted by Pope John Paul II to Pro-President of Vatican City, making him the third most powerful person in the Vatican, after the pope and the secretary of state. None of Yallop's claims, which are unproven, has thus far been acknowledged by the Vatican, although Yallop disclosed the Masonic Lodge numbers of the Curia members whom he alleged to be Freemasons in his book (it is forbidden by Church law for a Roman Catholic to be a Freemason).
Abbé Georges de Nantes
Traditionalist theologian Abbé Georges de Nantes spent much of his life building a case for murder against the Vatican, collecting statements from people who knew the Pope before and after his election. His writings go into detail about the banks and about John Paul I's supposed discovery of a number of Freemason priests in the Vatican, along with a number of his proposed reforms and devotion to Fátima. 
John Cornwell's book
In his book A Thief in the Night, British historian and journalist John Cornwell examines and challenges Yallop’s points of suspicion. Yallop’s murder theory requires that the pope’s body be found at 4:30 or 4:45 a.m., one hour earlier than official reports estimated. He bases this, inter alia, on an early story by the Vatican radio and Italian news service ANSA that garbled the time and misrepresented the layout of the papal apartments. Yallop claims to have had testimony from Sister Vincenza Taffarel (the nun who found the Pope's body) to this effect but refused to show Cornwell his transcripts.
Lucien Gregoire's book
Lucien Gregoire's highly speculative "investigations" into the sudden death of John Paul I claim to derive authority from an assertion that he personally knew Albino Luciani, through his own friendship with Luciani's personal assistant, whilst Luciani was Bishop of Vittorio Veneto. Gregoire, however, never names this "assistant" and never produces any documentation of this relationship. This same personal assistant was, supposedly, killed in a mysterious 'hit-and-run' accident, outside St Peter's, a few days after the death of his previous master. Again, no documentation is offered to support this assertion.
Gregoire's investigations claim to continue the work of Avro Manhattan, who he claims died in strange circumstances whilst visiting his familial home in South Shields, Tyne and Wear, in the United Kingdom. This claim is unsupported by the historical record. Gregoire asserts that Manhattan's death is one of the deaths allegedly associated with those who were close to, or supportive of, John Paul I. Gregoire's list of approximately thirty deaths includes papal predecessor Paul VI, the Belgian prelate Leon Joseph Suenens, Nikodim, the youthful Orthodox Metropolitan of Leningrad, and numerous senior members of the Swiss Guard.
The authenticity of Gregoire's self-published work is dismissed by scholars[who?] of the life and theology of John Paul I, and his more sensational claims remain unsupported by any corroborating source (despite numerous unsubstantiated references throughout).
Traditional Latin Mass
[Fr. DePauw] stated on the 15th anniversary of the Pope’s death: “Well, I tell you one thing, if he had remained Pope, you wouldn’t have me here at the Chapel because with that beautiful official letter signed by the Secretary of State, also came an unofficial message that I better start packing my suitcase, that there was a job waiting for me in Rome, in the Vatican, to help Pope John Paul I bring the Truth back to the Church. Well, it wasn’t to be and the Lord, Who knows what He does, obviously wanted me to be in this Chapel … what was I going to do in Rome? Well let’s just forget it …”
In popular culture
Malachi Martin's book Vatican: A Novel  is a novel based on recent papal history. Although officially a work of fiction, Martin proposes the theory that the pope was murdered by the Soviet Union because he would abdicate the benign policy of his two predecessors, John XXIII and Paul VI, towards accommodating communism, and once again condemn it as an atheistic totalitarian ideology. Martin believed that the church structure was infiltrated for decades by illuminati agents who reached positions of high influence and rank, such as Jean-Marie Villot, at that time Cardinal Secretary of State.
Lead singer of The Fall, Mark E. Smith wrote a play entitled Hey, Luciani, about the purported murder conspiracy, which was produced and performed in London. Several songs from the play were released as Fall singles.
Australian comedian Shaun Micallef wrote a one-act play entitled "The Death of Pope John Paul I". In it the pope is found in bed, sitting upright, unable to be woken. Two cardinals attempt to perform the ritualistic tapping with the silver hammer but no-one can locate the proper instrument, so they use a claw hammer instead.
The film The Pope Must Die takes its title from a passage in Yallop's book. The film's plot - a poor country priest named Albinizi becomes a reforming Pope, pitched against a corrupt and Mafia-riddled Vatican - is a parody of Luciani's career, ending in comedy rather than tragedy.
The Last Confession is a play written by Roger Crane. It is a thriller that tracks the dramatic tensions, crises of faith, and political manoeuvrings inside the Vatican surrounding the death of Pope John Paul I. The play toured the UK in the spring of 2007, before being transferred to the Theatre Royal, Haymarket, with a cast including David Suchet. It was subsequently broadcast on BBC Radio 4 on 4 October 2008. In October 2010 the play was brought to continental Europe by the Antwerp Theater Group "De Speling". Suchet reprised the role at the Ahmanson Theater in Los Angeles in July 2014 and the Comedy Theatre in Melbourne in September 2014.
The 1990 motion picture The Godfather Part III featured a story element depicting Società Generale Immobiliare, the largest real estate company in the world whose former largest shareholder was the Holy See, and the Vatican Bank involved in organized crime during and after the death of the old pope and the election of a fictional Cardinal named Lamberto to the papacy. Lamberto takes the papal name "John Paul I" and, like the real Pope John Paul I, he mysteriously dies.
A storyline in the comic book series Warrior Nun Areala features a flashback back to John Paul I's pontificate. Shortly after being elected to the papacy John Paul discovers a conspiracy of demon worshiping Freemasons in the Vatican and works to root them out. Discovered, the Masons kill him in order to continue their goal to destroy the Catholic Church. While John Paul does die, the Warrior Nuns manage to avenge him.
The 22nd episode of Brad Meltzer's Decoded "Vatican", featured theories and investigation on Pope John Paul I death.
- "BISHOP TELLS STORY OF POPE JOHN PAUL I'S DEATH HE DEBUNKS CONSPIRACY THEORY, BUTS SAYS VATICAN ALTERED SOME DETAILS". St. Louis Dispatch. October 11, 1998. Retrieved 31 December 2009.
- "Evidence of foul play in Pope death claimed". Chicago Tribune. Oct 7, 1978. Retrieved 26 December 2009.
- John Paul I at Catholic Counter-Reformation
- Chapter 4 of Whole Truth about Fátima, sections 7, 8 and 9, webpage found 2010-04-29.
- Quoted in Camillo Bassotto's book My Heart Is Still in Venice, a biography of John Paul I (Krinon, 1990).
- In his Angelus address for September 10, 1978, John Paul had already stated "E' papà; più ancora è madre, (He is father, even more he is mother)" quoting Isaiah 49:15 and 66:13.
- Marcinkus, at the time head of the Vatican Bank, was indicted in Italy in 1982 as an accessory in the $3.5 billion collapse of Banco Ambrosiano.
- Calvi murder: The mystery of God's banker, The Independent, June 7, 2007
- Summers, Chris (4 December 2002). "Call for third 'God's banker' inquest". BBC News.
- Declaration on Masonic Associations, Vatican website, in English.
- John Paul I at Catholic Counter-Reformation, Abbé de Nantes' website, in English.
- Cuneo, Richard (8 September 2013). "September 2013 News From CTM". latinmass-ctm.org. Catholic Traditionalist Movement. Retrieved 15 November 2013.
- "John Paul I May Have Been the "Traditional" Pope Prayed For: The Arguably-assassinated Pope Was Reportedly About to Restore the Traditional Latin Mass". traditio.com. 27 June 2011. Retrieved 15 November 2013.
- Potemra, Michael (28 September 2013). "Papa Luciani, 35 Years Later". nationalreview.com. National Review. Retrieved 15 November 2013.
- Martin, Malachi, Vatican: A Novel, Harper & Row, New York, 1986 ISBN 0-06-015478-0
- [ http://cultura.elpais.com/cultura/2014/02/17/actualidad/1392670188_619833.html elpais.com]
- Mark E Smith on JPI (New Musical Express, 13 December 1986
- NY Times: Was the Pope murdered? (5 November, 1989)
- "Catholic Counter-Reformation" essay on JPI
- A thorough critical discussion of Yallop and Cornwell's books
- "The Murder of Pope John Paul I: A study by the Abbé de Nantes" (article from the English CRC for October 1984)