Pope John Paul I, who died in 1978 after only 33 days as pontiff, has moved closer to sainthood but the Vatican still has to dismiss lingering conspiracy theories that he was a victim of foul play.

Pope Francis beatified his predecessor at a ceremony in St Peter’s Square before tens of thousands of people.

Beatification is the last step before sainthood in the Roman Catholic Church.

John Paul was known as ‘‘The Smiling Pope’’ because of his meekness and simplicity.

‘‘With a smile, Pope John Paul managed to communicate the goodness of the Lord,’’ Pope Francis said in his homily on Sunday, speaking as people huddled under umbrellas in a thunder storm.

‘‘How beautiful is a church with a happy, serene and smiling face, that never closes doors, never hardens hearts, never complains or harbours resentment, does not grow angry or impatient, does not look dour or suffer nostalgia for the past.’’

Born Albino Luciani into poverty in a northern Italian mountain village in 1912, he was ordained a priest in 1935, a bishop in 1958 and a cardinal in 1973.

He was elected pope on August 26, 1978, following the death of Pope Paul VI, taking the name John Paul to honour his two immediate predecessors.

Two nuns of the papal household who heard no response to knocks on his door early on September 29 to bring coffee found him dead in his bed.

Doctors said he died of a heart attack and aides said he had complained of chest pains the day before but did not take them seriously.

At first the Vatican, uneasy saying two women had entered the pope’s bed chambers, said he was found lifeless by a priest.

The Vatican corrected itself but the misstep sprouted conspiracy theories.

Although widely debunked, the idea of a pope being murdered in his bedroom in the 20th century irresistibly entered the collective consciousness and in the film The Godfather Part III, a pope named John Paul I is killed with poisoned tea.

‘‘There is no truth to it at all,’’ said Vatican Secretary of State Cardinal Pietro Parolin, when asked about the conspiracy theories on Italian television on Friday.

‘‘It is a shame that this story, this noir novel, goes on. It was a natural death. There is no mystery about it.’’

-Reuters