The Church’s call for nuclear disarmament

We have a responsibility to respond to Pope Francis’ call to counter the logic of fear and foster a climate of trust and dialogue.

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We still do not know how many people were killed by the atomic bombings of Hiroshima and Nagasaki: most estimates vary from 110,000 to 210,000 lives lost.11

In the aftermath, Pope Pius XII condemned nuclear bombs as “the most terrible weapon that the human mind has conceived up to date”,12 and Pope Paul VI later remarked that the bombings represented “butchery of untold magnitude”.13

It was two years prior to the events of August 1945 when Pope Pius XII first voiced the Church’s opposition to the use of atomic energy in warfare, warning that: “a dangerous catastrophe might occur, not only in the locality itself but also for our whole planet.”14 Since then, Catholic social teaching has been consistent and categorical: “Nuclear Weapons must be banned”,15 and their use should be considered a “crime against God and man himself. It merits unequivocal and unhesitating condemnation.”16

As the Holy See has highlighted, nuclear weapons are “fundamentally different from conventional weapons” given their potential to “cause damage on such a catastrophic scale as to wipe out a large part of civilisation and to endanger its very survival” and that “the large-scale use of such weapons could trigger major and irreversible ecological and genetic changes, whose limits cannot be predicted.”17 Pope Francis emphasised this in Laudato Si’, explaining that threats to “the environment and cultural riches of
peoples […] are magnified when one considers nuclear arms”.18

At the height of the Cold War, Pope John Paul II, whilst unequivocally opposing the use of nuclear weapons, accepted that minimal possession could be morally acceptable as a means of deterrence if this served as a step toward progressive global disarmament. He urged countries to “not be satisfied with this minimum, which is always susceptible to the real danger of explosion”19. This reflected the position set out by Pope John XXIII in Pacem in Terris, that the logic of deterrence is not an adequate strategy for long-term peace and that “true and lasting peace among nations cannot consist in the possession of an equal supply of armaments but only in mutual trust”.20

Today, however, many nations including the UK still rely on the logic of deterrence as a justification for continued possession, maintenance, or even expansion of their nuclear arsenals. Pope Francis reaffirmed the Church’s opposition to this in Fratelli Tutti, stating: “International peace and stability cannot be based on a false sense of security, on the threat of mutual destruction or total annihilation […] In this context, the ultimate goal of the total elimination of nuclear weapons becomes both a challenge and a moral and humanitarian imperative.”21

The Holy See’s contribution to the Non-Proliferation Treaty (NPT) review conference in 2022 underscored that: “Trying to defend and ensure stability and peace through a false sense of security and a ‘balance of terror’ ends up poisoning relationships between peoples and obstructs real dialogue”. It also encouraged signatories “to adopt a renewed conviction of urgency and commitment to achieve concrete and durable agreements towards nuclear disarmament and non-poliferation”.22

Writing to Bishop Alexis-Mitsuru Shirahama of Hiroshima the following year, Pope Francis again warned against “the continuing climate of fear and suspicion” created by the mere possession of nuclear weapons and stated that they “represent a multiplier of risk that offers only an illusion of peace”.23 Furthermore, Fratelli Tutti explains that nuclear weapons are an inadequate response to the principal security threats facing humanity today, such as terrorism, asymmetrical conflicts, cybersecurity issues, climate change, and poverty.24

Another persistent focus for the Church has been challenging the vast sums spent on developing, upgrading, and maintaining nuclear weapons and the decisions of governments to invest colossal human, economic and political resources away from the global common good and towards the ‘balance of terror’.

Reflecting Pope Paul VI’s call in Populorum Progressio for governments to “set aside part of their military expenditures for a world fund to relieve the needs of impoverished people”,25 the Holy See’s contribution to the Vienna Conference on the humanitarian impact of nuclear weapons in 2014 stated explicitly that: “maintenance of the world’s nuclear weapons establishment results in misallocation of human talent, institutional capacities, and funding resources. Promotion of the global common good will require re-setting those allocations, re-ordering priorities toward peaceful human development.”26

Here in the UK, our Bishops have affirmed that “the cost of nuclear weapons should be measured not only in the lives destroyed through their use, but also the suffering of the poorest and most vulnerable people, who could have benefited were such vast sums of public money invested in the common good of society instead.”27 Likewise, when the UK Government announced plans to increase the country’s nuclear arsenal, Christian leaders came together to emphasise the immorality of “committing resources, which could be spent on the common good of our society, to stockpiling even more [nuclear weapons].”28

Drawing these themes together, Pope Francis explicitly sets out that not only the use or threatened use of nuclear weapons but also “their very possession” is to be firmly condemned.29 He has reaffirmed this on several occasions including at the peace memorial in Hiroshima, where he stated that “the use of atomic energy for purposes of war is immoral, just as the possessing of nuclear weapons is immoral.”30

The Church has persistently called for those states possessing nuclear weapons to disarm, including our Bishops encouraging successive governments to forsake the UK’s nuclear arsenal.31 We recognise that while, each State has a moral responsibility for its own disarmament, this will most effectively be progressed through international frameworks. For this reason, the Holy See has been a leading force behind the Treaty on the Prohibition of Nuclear Weapons (TPNW), the first legally binding instrument to prohibit the development, testing, production, stockpiling, stationing, transfer, use and threat of use of nuclear weapons. Archbishop Paul Gallagher, as Vatican Secretary for Relations with States, described this as “one more blow on the anvil toward the fulfilment of the prophecy of Isaiah: ‘They shall beat their swords into ploughshares and their spears into pruning hooks’.”32

The treaty was born out of a desire, among many states and different parts of civil society, to reinvigorate progress towards global nuclear disarmament. In 2008, Pope Benedict XVI appealed: “At a time when the process of nuclear non-proliferation is at a standstill, I feel bound to entreat those in authority to resume with greater determination negotiations for a progressive and mutually agreed dismantling of existing nuclear weapons. In renewing this appeal, I know that I am echoing the desire of all those concerned for the future of humanity”.33

The Holy See has been consistently clear that the TPNW complements the NPT, which since 1968 has formed the cornerstone of global disarmament efforts, observing that the TPNW “mutually reinforces the nuclear non-proliferation regime, especially Article VI of the NPT, which calls for ‘effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament.’”34 This is an important reminder that, while we are called to work for disarmament of existing nuclear stockpiles, it is also essential to support diplomatic efforts to prevent the spread of nuclear weapons to other countries.

During negotiations on the TPNW in 2017, Pope Francis repeated calls for full implementation of the NPT, while characterising the new treaty as “an exercise in hope”, going on to state: “it is my wish that it may also constitute a decisive step along the road towards a world without nuclear weapons […] although this is a significantly complex and long-term goal, it is not beyond our reach.”35

Specific steps towards fulfilment of the treaty were set out in the Vienna Declaration and Action Plan adopted at the first meeting of signatories in 2022.36 In its contribution to the meeting, the Holy See reiterated its call for every country to join TPNW, for those who have not yet joined to participate as observers at future meetings, and for all to seek constructive engagement with the TPNW regime.37 This has been echoed by the Church in many countries that have yet to join, including here in the UK.38

The TPNW, along with the Vienna Declaration and Action Plan, also includes important steps to assist victims and communities affected by nuclear testing. The Holy See has highlighted that these tests have had a “disproportionate impact on women, girls, and the unborn” and were often accompanied by “forced displacements, the desecration of cultural heritage, and debilitating public health issues” for which nuclear-armed states have a moral obligation to provide redress for.39 This is applicable to the UK’s own legacy of nuclear testing.40

It is important to reinforce that, while the Church strongly supports multilateral disarmament efforts, including through the NPT and TPNW, Catholic teaching is also clear that “a world without nuclear weapons is not simply the present world minus nuclear weapons”.41 Rather, nuclear disarmament is an integral aspect of wider disarmament efforts which, in turn, are one component of building the “enterprise of justice” called for by the Second Vatican Council in Gaudium et Spes.42

Action Points

The UK is one of the few nuclear-armed states in the world. As the Catholic Church in England and Wales, we therefore have a particular responsibility in responding to Pope Francis’ call that: “Now is the time to counter the logic of fear with the ethic of responsibility, and so foster a climate of trust and sincere dialogue.”43

Through our prayer and public witness, we seek for the UK to:

  • Ultimately forsake its nuclear arsenal, helping to create a world without nuclear weapons
  • Fulfil its obligations under the Non-Proliferation Treaty to pursue an end to the nuclear arms race, to advance multilateral disarmament, to refrain from expanding its own arsenal, and to work towards reducing it at the earliest opportunity
  • Sign and ratify the Treaty on the Prohibition of Nuclear Weapons, and, until this point, engage meaningfully with the treaty framework including participating as an observer in future meetings of signatories
  • Redirect the economic, social and political resources spent on nuclear weapons towards promoting the universal common good


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11 Bulletin of the Atomic Scientists, Counting the dead at Hiroshima and Nagasaki, 4 August 2020.

12 Pope Pius XII, Address to the Plenary Session of the Pontifical Academy of Sciences, 8 February 1948.

13 Pope Paul VI, Message for the World Day of Peace, 1 January 1976.

14 Pope Pius XII, Address to the Plenary Session of the Pontifical Academy of Sciences, 21 February 1943.

15 Pope John XXIII, Pacem In Terris, [112], 1963.

16 Second Vatican Council, Gaudium Et Spes [80], 1965.

17 Pontifical Academy of Sciences, Declaration on Prevention of Nuclear War, 1982.

18 Pope Francis, Laudato Si’ [57], 2015.

19 Pope John Paul II, Message to the General Assembly of the United Nations, 7 June 1982.

20 Pope John XXIII, Pacem in Terris [113], 1963.

21 Pope Francis, Fratelli Tutti [262], 2020.

22 Holy See, Treaty on the Non-proliferation of Nuclear Weapons: ethical dimensions and security challenges, 27 July 2022.

23 Pope Francis, Letter to the Bishop of Hiroshima on the occasion of the G7 Summit, 19 May 2023.

24 Pope Francis, Fratelli Tutti [262], 2020.

25 Pope Paul VI, Populorum Progressio [51], 1967.

26 Permanent Mission of the Holy See to the United Nations and Other International Organisations in Geneva, Nuclear Disarmament: Time for Abolition, 8 December 2014.

27 Catholic Bishops Conference of England and Wales, Statement on nuclear weapons, 4 August 2020.

28 Catholic Bishops’ Conference of England and Wales, Catholic Bishops oppose increase in Trident Nuclear Warhead numbers, 16 March 2021.

29 Pope Francis, Address to Participants in the International Symposium ‘Prospects for a world free of nuclear weapons and for integral disarmament’, 10 November 2017.

30 Pope Francis, Address at the Hiroshima Peace Memorial, 24 November 2019.

31 Catholic Bishops’ Conference of England and Wales, Statement on the Treaty on the Prohibition of Nuclear Weapons, 11 January 2021.

32 Archbishop Paul Gallagher, Intervention to the United Nations General Assembly on Striving for Peace and a Decent Life on a Sustainable Planet, 25 September 2017.

33 Pope Benedict XVI, Message for the World Day of Peace, 1 January 2008.

34 Pope Francis, Message to His Excellency Ambassador Gustavo Zlauvinen, President of the Tenth Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons, 22 August 2022.

35 Pope Francis, Message to Her Excellency Elayne Whyte Gómez President of the United Nations Conference to Negotiate a Legally Binding Instrument to Prohibit Nuclear Weapons, Leading Towards their Total Elimination, 23 March 2017.

36 ICAN, Vienna Declaration and Action Plan: Overview, [Accessed 26 March 2024].

37 Holy See, Contribution to the First Meeting of States Parties to the Treaty on the Prohibition of Nuclear Weapons: The Treaty On the Prohibition of Nuclear Weapons – A Path for Dialogue and Action, 2022.

38 Catholic Bishops’ Conference of England and Wales, Statement on the Treaty on the Prohibition of Nuclear Weapons, 11 January 2021.

39 Archbishop Gabriele Caccia, General Assembly High-Level Plenary meeting to commemorate and promote the International Day Against Nuclear Tests (IDANT), 7 September 2022.

40 United Nations Association – UK and Article 36, Addressing British nuclear tests in Kiribati, June 2022.

41 Stephen Colecchi, Preliminary Conclusions in A World Free from Nuclear Weapons: The Vatican Conference on Disarmament (edited by Fr Drew Christiansen SJ and Carole Sargent), 2020.

42 Second Vatican Council, Gaudium Et Spes [78], 1965.

43 Pope Francis, Message to the Vienna conference on the humanitarian impact of nuclear weapons, 7 December 2014.