Vatican City: As conflicts continue across the world, recent reflections from the Vatican highlight a strong and growing message from the Church that war is no longer a solution in the modern age.
From the time of Pope Benedict XV, who described the First World War as an “useless slaughter,” to the present leadership of Pope Leo XIV, the Catholic Church has steadily deepened its teaching on peace and the moral limits of war.
In 1963, Pope John XXIII warned in his encyclical Pacem in Terris that in the atomic age, it is almost impossible to justify war as a means of justice. This marked a turning point in the Church’s thinking, as the destructive power of modern weapons began to reshape moral considerations.
Later, Pope Paul VI brought this message to the global stage with his powerful appeal at the United Nations, calling on the world to reject war entirely. Pope John Paul II also repeatedly urged leaders to avoid conflict, especially during crises in the Middle East, though many of his appeals went unheard.
The Church’s official teaching, found in the Catechism of the Catholic Church, still allows for self defense but under very strict conditions. These include the certainty of grave harm, the exhaustion of all peaceful options, and the need to ensure that the use of force does not cause greater damage than the original threat. However, with the rise of advanced weapons and technologies, meeting these conditions has become increasingly difficult.
This concern was strongly echoed by Pope Francis in his 2020 encyclical Fratelli tutti. He warned that modern wars are often justified using misleading arguments and that today’s weapons give humanity an unprecedented and dangerous level of power. He stressed that war can no longer be seen as a viable solution, as its risks far outweigh any possible benefits.
Continuing this path, Pope Leo XIV has made peace a central focus of his pontificate. Speaking during a prayer vigil on April 11, he called on people to reject violence and instead choose dialogue and understanding. He warned against a world driven by power, fear, and selfish interests, and urged a return to values that protect life and human dignity.
As civilian suffering increases in many parts of the world, the voices of the Popes over the past century form a consistent and urgent appeal. Their message is clear that in a time of powerful weapons and global tensions, humanity must move away from war and choose peace.