Only time will tell what impact the recent visit of Pope Francis to Ireland will have on the future of the Catholic Church in this country.

But the focus has already shifted back to the previous papal visit to Ireland in 1979, with a new historical documentary making the case that Pope John Paul's trip was instrumental in ending The Troubles and bringing about peace in Northern Ireland.

The film, "John Paul II in Ireland: A Plea for Peace," claims that the late pontiff's visit marked the beginning of the peace process after he made an impassioned appeal during his stopover in Drogheda for an end to the violence and bloodshed.

Carl Anderson, the U.S.-based executive producer of the documentary and head of the Knights of Columbus said, "At Drogheda, Ireland, he took an axe and cut its roots.  It would take some time for this poisonous tree to wither, but eventually, it would."

Filmmaker David Naglieri, who spent 18 months on the project, said the most eye-opening interview he conducted was with former IRA member Shane O'Doherty.

O'Doherty, who was an explosives expert, infamously carried out a letter-bombing campaign in London, targeting 10 Downing Street, the London Stock Exchange, the Bank of England—along with attempting to kill the chief Catholic chaplain to the British Army, Bishop Gerard Tickle.

Read more: As Pope Francis lands in Ireland, we remember John Paul II's 1979 visit

But while in prison, he publicly renounced violence after listening to the homily John Paul gave at Mass in Drogheda.  He went on to publicly renounce his connection to the IRA, and wrote letters to his victims while in jail in England.

In an interview with the Catholic News Service, Naglieri said, "John Paul II preaching peace was the wind between his wings."

He added, "John Paul II told politicians that they must remove the causes that lead to violence, and said that political dialogue is the way forward."

Read more: Close-lipped Pope Francis fails to make his mark in Ireland

It's estimated that between 150,000 and 200,000 people attended Pope Francis' recent Mass in Dublin's Phoenix Park, a figure that is far less than had been anticipated, and a fraction of the 1.25 million who flocked to see the late Polish pontiff back in 1979.

The historic visit was the first by a pope to Ireland and marked the centenary of the apparitions of the Blessed Mother at Knock in August 1879.

A keenly anticipated screening of "John Paul II in Ireland: A Plea for Peace" is taking place at London's Westminster Cathedral on Sunday, September 16.

What was the largest difference you notice between the Pope's visit? Let us know in the comments section, below. 

The film, "John Paul II in Ireland: A Plea for Peace," claims that the late pontiff's visit marked the beginning of the peace process.