The Popes since WWII: Almost a century of fighting for disarmament

By Francesca Merlo

In the last eighty years, the Popes have been at the forefront in the struggle for peace. Condemnation for weapons and the arms trade have been recurrent throughout the decades, shaping and strengthening the Catholic Church’s stance on these issues.

Pius XII and warnings of a future catastrophe

Pope Pius XII, who served as Pope from 1939-1958 witnessed firsthand the horrors of World War II and, with it, the dawn of the nuclear age. In his 1948 Christmas message, he spoke out against the arms race, stating that while nations have a right to self-defense, the accumulation of destructive weapons endangers humanity. He stressed that disarmament could only be achieved through international agreements built on trust.

He prayed for peace, “precisely at a time when humanity, crushed under the weight of armaments, anguished by the prospect of new and more serious conflicts, trembles at the mere thought of a future catastrophe”.

“The Christian will for peace also has its own weapons. But the main ones are prayer and love: constant prayer to the Heavenly Father, Father of us all; fraternal love among all men and all peoples.”

John XIII and the need to ban nuclear weapons

Shortly afterwards came the Cold War, and with it the even more real threat of nuclear warfare. Pope John XXIII, who held the papacy from 1958-1963, published his encyclical Pacem in Terris ("Peace on Earth," 1963), shortly after the Cuban Missile Crisis, and as US President John Kennedy sent more troops to fight in Vietnam.

John XXIII’s encyclical is dedicated to ending the arms race and advocating for a world free from nuclear weapons. He argued that peace cannot be based on fear but must be rooted in respect for human rights and dialogue between nations.

“Justice, right reason, and the recognition of man's dignity cry out insistently for a cessation to the arms race. The stock-piles of armaments which have been built up in various countries must be reduced all round and simultaneously by the parties concerned. Nuclear weapons must be banned. A general agreement must be reached on a suitable disarmament program, with an effective system of mutual control.”

Pope Paul VI and the cry for money wasted on arms

In 1965, two years after he was elected to the See of Peter, Pope Paul VI addressed the United Nations, delivering a historic appeal for peace. He famously declared, "No more war, war never again!"

He pushed for disarmament, arguing that the vast resources devoted to the military could instead be used to fight poverty and improve the lives of millions. His encyclical Populorum Progressio (1967) reiterated this point, linking disarmament to global development.

“Countless millions are starving, countless families are destitute, countless men are steeped in ignorance; countless people need schools, hospitals, and homes worthy of the name. In such circumstances, we cannot tolerate public and private expenditures of a wasteful nature; we cannot but condemn lavish displays of wealth by nations or individuals; we cannot approve a debilitating arms race. It is Our solemn duty to speak out against them. If only world leaders would listen to us, before it is too late!”

John Paul II and disarmament needed to match ethical renewal

Pope John Paul II, too, was a vocal advocate for peace, especially during the Cold War. He constantly called for nuclear disarmament and the de-escalation of military conflicts.

In his 1982 speech to the United Nations, he warned that the buildup of nuclear weapons would lead to unimaginable destruction. “Like peace, the world wants disarmament; the world needs disarmament”, he said whilst addressing the General Assembly. He also emphasised that true security comes not from the military might but from justice, dialogue, and respect for human dignity. 

“The production and the possession of armaments are a consequence of an ethical crisis that is disrupting society in all its political, social and economic dimensions. Peace, as I have already said several times, is the result of respect for ethical principles. True disarmament, that which will actually guarantee peace among peoples, will come about only with the resolution of this ethical crisis. To the extent that the efforts at arms reduction and then of total disarmament are not matched by parallel ethical renewal, they are doomed in advance to failure”.

John Paul II’s 1991 encyclical Centesimus Annus reinforced the idea that peace and development go hand in hand, and that a commitment to disarmament should be part of a broader effort to create a just international order.

Benedict XVI and the need for welfare over militarisation

Pope Benedict XVI was faithful to the appeals to his predecessors. In his 2006 World Day of Peace message, one year into his pontificate, he warned that "in a nuclear war, there would be no victors, only victims."

He urged world leaders to work for the total elimination of nuclear weapons and highlighted the need for moral leadership in promoting disarmament.

"One can only note with dismay the evidence of a continuing growth in military expenditure and the flourishing arms trade, while the political and juridic process established by the international community for promoting disarmament is bogged down in general indifference. How can there ever be a future of peace when investments are still made in the production of arms and in research aimed at developing new ones?"

In his encyclical Caritas in veritate, Pope Benedict also called for responsible policies that prioritise human welfare over militarisation.

"If such efforts are to have lasting effects, they must be based on values rooted in the truth of human life. That is, the voice of the peoples affected must be heard and their situation must be taken into consideration, if their expectations are to be correctly interpreted. One must align oneself, so to speak, with the unsung efforts of so many individuals deeply committed to bringing peoples together and to facilitating development on the basis of love and mutual understanding".

Pope Francis and the shame in making profit from death

Finally, Pope Francis has tirelessly called for peace worldwide, recalling some of the most forgotten and often most horrific conflicts currently plagueing our world today.

Pope Francis has also been critical of the global arms trade, linking it to wars and conflicts that devastate communities, particularly in poorer regions. His 2020 encyclical Fratelli tutti underscored the moral imperative for disarmament, stressing the importance of fraternity, global solidarity, and dialogue.

"Rules by themselves will not suffice if we continue to think that the solution to current problems is deterrence through fear or the threat of nuclear, chemical or biological weapons."

He condemned the use of resources for arms instead of addressing social inequalities, echoing the teachings of Popes before him. 

"With the money spent on weapons and other military expenditures, let us establish a global fund that can finally put an end to hunger and favour development in the most impoverished countries, so that their citizens will not resort to violent or illusory solutions, or have to leave their countries in order to seek a more dignified life".