ONCE MORE: NO TO WAR
When one speaks of war in ethical and Christian perspective, he or she will most probably think of “the Just War Theory”.
In the past, and up to the twentieth century, wars seemed to be inevitable and the application of the Just War Theory, an ethical demand – or excuse – to go to war and to defend wars. After the September 11, 2001 terrorist attacks against the Twin Towers in New York and the Pentagon in Washington D.C., the Just War Theory was “resurrected” again. President George W. Bush and other world leaders used the Just War Theory to justify the war - and not only against terrorism.
The Just Theory war came up again repeatedly to justify some wars (2022-2026). May we speak today of a just war?
WARS AND THE “JUST WAR”
War is understood as an armed conflict between armies of enemy States. In the current context, war is also understood as an armed conflict between a State – or many States – and organized social groups or organizations similar to States, for instance terrorist groups.
There are different kinds of war. For our purpose, we point out mainly two. We speak of offensive war (unprovoked war against another State), and defensive war (war against an unjust aggressor). Furthermore, we may speak of preventive war (going to war to prevent the threat of war from another State). Besides, and considering the weapons of destruction used, we talk of nuclear, bacteriological or chemical wars.
The expression “just war” was coined by Aristotle and other Greek philosophers. The Just War Theory was proposed and defended by the two great theologians St. Augustine and St. Thomas Aquinas. The classical explanation is St. Thomas’, found in question 40 of his Summa Theologiae II-II.
The Angelic Doctor ask ed himself: Is it always a sin to wage war? (Hence, he is against all wars, in general). Generally, it is immoral and unchristian to wage war: it is a vice against charity, which is peaceful. How about in some exceptional cases? Exceptionally, war can be licit – ethical and justifiable - if it fulfills three rigorous conditions, namely, it is called by public authority, there is a just cause, and the intention is right, that is, for the sake of justice and peace.
The most difficult condition to carry out is the second: going to war for a just cause. A just cause requires the fulfillment of four strict rules: (1) The presence of grave injustice obstinately pursued; (2) The need to make recourse to war to obtain justice; (3) Proportion between the gravity of the injustice and the calamities to ensue from the war (the principle of “double effect” and “the lesser evil”); (4) A realistic probability of victory.
Obviously, St. Thomas’ doctrine of the just war, within the treatise of charity not only justice, is ordered to avoid wars. Why? Because it is almost impossible to fulfill all the conditions ad bellum and in bello (to go to war and during the war). St Augustine says that “it is a higher glory to procure or maintain peace by peace, not by war.” (cf. Pope Francis, Fratelli Tutti, FT, footnote 242).
MAGISTERIUM OF THE CHURCH
Regarding the teaching of the Church on the just war, there is a harmonious development of doctrine. Vatican II (1962-1965) closes the door a little more to the possibility of a just war in the context of nuclear weapons and the arms race. Vatican II states: “War today must be evaluated with an entirely new attitude.” “It is our clear duty to strain every muscle as we work for the time when all wars can be completely outlawed by international consent.” Vatican II continues to speak of the right – and duty – of legitimate defensive war as a last resort (cf. Gaudium et Spes, nn. 79, 80 and 82).
In his encyclical Pacem in Terris (no. 55), Pope John XXIII is strongly against war in the new context of nuclear weapons: “In this age which boasts of an atomic power, it no longer makes sense to maintain that war is a fit instrument with which to repair the violation of justice.” From the podium of the United Nations in New York, Pope Paul VI cried out (October 4, 1965): “No more war! War never again! Peace, it is peace which must guide the destinies of peoples and all mankind.” In his Message for the 1982 World Day of Peace, Pope John Paul II spoke of war in general and of defensive war in particular. The Polish Pope said that Christians strive “to resist and prevent every form of warfare,” for war is “the most barbarous and least effective way of resolving conflicts.” Nevertheless, facing grave injustice, Christians favor the collective defense of society in the name of justice: “In the name of an elementary requirement of justice, people have a right and even a duty to protect their existence and freedom by proportionate means against an unjust aggressor.” This traditional teaching, however, is harder to apply – if at all possible - in the context of the new deadly weapons.
The Catechism of the Catholic Church (CCC) speaks of war within the fifth commandment: Thou shall not kill. It presents with brevity and clarity the teaching of the Church, particularly the conditions for a just war - after Vatican II (CCC, n. 2309; cf. Ibid. nn. 2307-2317).
Pope Francis spoke frequently against war and wars. The Argentine Pope speaks of the negative effects of wars on the environment and on the poor. War and the death penalty, he tells us, are “false answers” that do not resolve the problems they are meant to solve,” but “introduce new elements of destruction in the fabric of national and global society” (FT, 255); cf. Ibid. n. 255-270). War is not “a ghost from the past but a constant threat” (FT, 256). War implies “the negation of all rights .and a dramatic assault on the environment.” Indeed, “Every war leaves our world worse than it was before. War is a failure of politics and of humanity, a shameful capitulation, a stinging defeat before the forces of evil” He underlines “the injustice of collateral damage” (FT, 261). Indeed, in the context of nuclear, chemical and biological weapons, and the enormous growing possibility of new technologies,” there is the grave danger of not using them wisely. Hence, “we can no longer think of war as a solution, because its risks will probably always be greater than its supposed benefits.”
In this new context, “it is very difficult nowadays to invoke the rational criteria elaborated in earlier centuries to speak of the possibility of a ‘just war’. Never again war!” Pope Francis maintains that the concept of “just war,” no longer be upheld today (FT, 258). The Pope frowns, too, on “the possibility of legitimate defense by means of military force,” and thinks, moreover, that “preventive attacks or acts of war entail “evils and disorders graver than the evil to be eliminated” (FT, 258).
Pope Leo XIV speaks often against war and for peace and reconciliation, and in favor of dialogue among nations and their respective governments. Th North American Pope repeat similar words in every country he visits: “I am here to proclaim peace” (Cameroon, April 14, 2026).
There is furthermore, from Vatican II up to Pope Leo XIV, a firm condemnation of the arms race as a mens of deterrence. Vatican II considers the arms race “an utterly treacherous trap for humanity” that harms the poor immensely (Gaudium et Spes, no. 81). Pope John XXIII rejected deterrence and proposed a progressive disarmament. Pope Paul VI deplored deterrence for it does not remove but aggravates the risks of war, and also because it leaves the poor poorer: every exhausting armament’s race is an intolerable scandal (opulorum Progressio, no. 53). Pope Francis speaks of “the inadequacy of nuclear deterrence as an effective response” to the challenges posed. “International peace and stability cannot be based on a false sense of security, on the threat of mutual destruction or total annihilation, or on simply maintaining a balance of power.” He advocates for the establishment of “a global fund” fed by the money to be spent on weapons and other military expenses (cf. FT, 262).
It used to be said: Si vis pacem, para bellum (if you want peace prepare for war). Today we say: Si vis pacem, para pacem (If you want peace, prepare for peace). As Gandhi repeated, “There is no way to peace, peace is the way”. For Jesus Christ, we walk to peace by the path of justice and love. The Psalmist proclaims: Justice and peace kiss each other” - on the bridge of love. (Love or charity necessarily requires justice and goes higher: it makes every other not just an equal but a brother or sister). With many others, Christians are asked by their humanity and faith to be artisans of peace in a world at war. Those of us who are for peace and are against wars try seriously to live just, compassionate, peaceful lives and, united, proclaim peace as the only way to peace.
One may not speak ethically against war (aren’t we all against wars?) if there is no coherence among basic ethical principles. Being against war and for dictatorships of the right or the left becomes not credible. Fundamental human rights must be respected and defended by all.
The fifth commandment continues voicing out: “Thou shall not kill”. It is interesting to note that the first Christians should neither be soldiers nor judges: the soldiers may kill, and the judges may send “criminals” to death row for punishment with the death penalty.
Once more, as a human being and as a Christian, as a brother in our common humanity, let me cry out:
NO MORE WAR. WAR, NEVER AGAIN. (FGB)