A history of popes called Leo and what Pope Leo XIV means for the Church today

Thomas Casemore• May 12, 2025

On 8 May Catholics worldwide celebrated as white smoke rose above the Sistine Chapel and Cardinal Robert Prevost became the first American pope.

Many have been wondering what direction this papacy will take. Pope Francis, for all his positives, has left the Church in a more divided state than he found it, and so there is apprehension as to whether our new pope might become a divisive Francis II-esque figure, if not in name, then in action.

However, for those fearing this, our new Pope has given two important signs to the contrary. Firstly, unlike Pope Francis, he appeared on the balcony in the full papal regalia. Secondly, he chose the longstanding papal name “Leo” – meaning “lion” – symbolising strength and bravery.

Given our new Holy Father is still relatively unknown beyond his comments about wishing to be a peacemaker, it is worth looking at some previous Popes Leo and their impact on unity in the Church.

Pope Leo the Great (440-61)

Pope Leo I reigned at a time of great tragedy and turmoil for Rome.

The Roman Empire had moved to Constantinople, and the Western half of the empire was collapsing under barbarian raids. Atilla the Hun had made incursions into Italy in 452, sacking cities on his way to Rome.

Leo I negotiated and made peace with Attila, which saved Rome from invasion and caused the Huns to withdraw from Italy.

Sadly, the same did not work when in 455 the Vandal King Genseric sacked Rome. However, Leo I did prevent the sacking of several basilicas in which many civilians had taken refuge. And after the ransacking, he assisted in the rebuilding of Rome.

Leo I was more than a peace negotiator however, playing a crucial part in the formation of the modern papacy.

He re-emphasised the role of papal authority within the Church at a time when Rome had lost its political standing to Constantinople, citing the primacy of St Peter among the apostles as evidence of his authority.

His most notable work, the Tome, was deeply influential on the proceedings at the Council of Chalcedon, and specifically in defining Christ’s hypostatic union as being of two natures (God and Man), not one (the Christ-nature).

These doctrinal affirmations led to the first large split between the Miaphysite Oriental Orthodox Churches and the Chalcedonian faith.

The Tome was meant to have been delivered at the Second Council of Ephesus in 449, but did not play a role until Chalcedon, at which the acts of the council record the proclamation, “Peter has spoken through Leo”.

Leo’s contributions to the saving of Rome, his theological works, and his re-affirmation of papal authority earned him the title “Great’” as well as his being named Doctor of the Church in 1754.

Pope Benedict XVI said of Leo I in 2008, that he was “undoubtedly one of the most important [popes] in the Church’s history”.

Pope Leo IX (1049-54)

Pope Leo IX is notable for presiding over the Great Schism between East and West.

His disagreements with the Patriarch of Constantinople, Michael I Cerularius, and his citing of the forged document (although this was not known to him) Donations of Constantine to claim papal authority over the Western Roman Empire led to the Great Schism of 1054.

Although the excommunications of one another by the papal envoy Cardinal Humbert and the Patriarch happened after Leo IX’s death, it was his envoy, and so he often carries part of the blame for the schism.

Included in the excommunication reasons, notably, was that the Byzantines refused to use the filioque formula of the Nicene Creed.

Pope Leo X (1513-21)

If the Great Schism wasn’t enough to damage the name Leo, it was sadly under another Leo that the Protestant Reformation and schism occurred.

Pope Leo X is noted as having once said “let us enjoy the papacy since God has given it to us”.

His lavish spending and patronage of expensive art showed that this Medici pope was more focused on worldly goods than spiritual fatherhood. Furthermore, to fund his renaissance image, he allowed the sale of indulgences in the Church.

It is this move that was the catalyst for Martin Luther in 1517 and his infamous 95 Thesis. Leo X did not engage theologically or seriously with Protestant concerns, instead excommunicating Luther and triggering a wider reformation.

Pope Leo XIII (1878-1903)

Finally, and perhaps most importantly, there was Pope Leo XIII.

Whilst Leo XIII is notable for highlighting the importance of Thomistic philosophy in the face of secularism in Aeterni Patris, as well as his desire for unity with the Orthodox Churches, he is most known for his social teaching.

Leo XIII was writing at a time of great global tumult. In Europe especially, revolutions and wars were brewing as communism grew, and exploitative capitalism was devasting the working classes.

He became known as the “worker’s pope” as he challenged wealthy industrialists to honour the human dignity of their workers; to pay fair wages, improve working conditions, and uphold the rights of workers to form unions.

In addition to this, he was also deeply opposed to communism and the growing secularisation in Europe. He particularly highlighted private property as the way of best distributing the earth’s wealth and condemning the socialist abolition of God.

Our new pope Leo said on 10 May that he chose his name because of Leo XIII and his crucial encyclical Rerum Novarum. So, what about our new Leo?

Pope Leo XIV (2025-)

In his first few addresses, Pope Leo XIV has called for peace. He has even taken the papal motto in illo uno unum, “In the One, we are one”.

Three of our noted Leos presided over the greatest schisms in God’s Church (Oriental, Eastern, and Protestant). Leo XIII, on the other hand, was a unifier.

Citing the latter gives an indication that Leo XIV is a peace maker, condemning both the uncaring capitalism and destructive socialism of our day.

As the first US-born Pope at a time when the US is under the very capitalist Donald Trump, and following the socialist-leaning Francis, choosing a name which stands in the void between the two is a promising sign for Church unity.

Beyond internal Church squabbles however, in the year of the 1700th anniversary of Nicaea, let us pray that this Leo works for the healing of the schism between East and West, and the divisions with our Protestant and Oriental Orthodox brethren.

Whilst other Leo’s caused division, may this Leo heal and unify.

Photo: William Bruns 1878 portrait of Pope Leo XIII