All religions need to examine how they contribute to the common good, which includes more people than those who follow a particular religion. The United Nations Secretary General's recent invitation to all religious and spiritual leaders to examine how they contribute to creating a culture of justice and peace for the world community provides an ideal opportunity for that examination. A central part of that culture for Christians is their attitudes toward war and peacemaking. Those attitudes have evolved dramatically over time, especially in the last century.
Christianity has gone through many changes with regard to war and peacemaking, beginning with the first few centuries when Christians refused to join Rome's Imperial Army, to the first elaborations of the Just War doctrines beginning in the third century, to the Crusades in the medieval period, and to the present day when the largest single group of Christians, Roman Catholics, officially have made the criteria for a just war more difficult to meet than ever and have begun to elaborate the requirements for peacemaking. Among themselves, however, the world's over two billion Christians continue to disagree on these matters, with some groups supporting preemptive military actions and others pacifism.
Historically speaking, the position of Christians in the world has no doubt affected their understanding of the morality of war and peacemaking. The New Testament texts themselves never directly address the morality of war, although the example of Jesus, especially as he faced Ms own death, suggests a strong non-violent attitude. The earliest Christians, a small minority tucked into the seams of the huge Roman Empire, could adopt (without much notice) a pacifist position. But with the passage of time, however, Christians entered the military, and religious leaders were forced to reflect more systematically on the morality of armed conflict. Once Christianity had become the official religion of the Roman Empire, Augustine (354-430) elaborated a theory about when war could be "justified" morally: namely as a response of love to a neighbor who has been threatened by force.
Thomas Aquinas (1225-1274) developed the idea of the "just war" further by legitimating self-defense as a reason for war. Throughout the Middle Ages, however, popes themselves not only called for the Crusades to reclaim the Holy Land from the Muslims, but also did not hesitate to use force to protect their interests and to enforce their policies. It was not until the papacy was forcibly stripped of the papal states by Italian nationalists in 1870 that the pope's exercise of power shifted dramatically to the moral and spiritual dimensions of leadership. Pope Benedict XV (1914-1922) tried unsuccessfully to end World War I and to create an international alliance among the nations of the world. In 1944, a year before President Truman approved the use of the atomic bomb over Japan, an influential Jesuit moral theologian published an article that condemned saturation bombing.
Pope John XXIII (1958-1963) initiated a richer and broader vision of war and peacemaking when he reiterated in a fresh and compelling way the need for an international body with responsibility for defining and defending human rights. Just two years after Pope John's death, his successor, Pope Paul VI (1963-1978) spoke before the United Nations and cried out, "No more war, war never again!" One of the documents of Vatican II (1962-1965) flatly condemned total war and called for political leaders, indeed all people of good will, to approach war with a totally new attitude; that text (Gaudium et spes) also endorsed non-violent resistance. In later encyclicals, Pope Paul identified the work for justice as the basis for a lasting peace. From 1870 to 1978, therefore, a profound shift had begun to take place in the Catholic teaching about war and peacemaking.
More than any other pope in modern history, Pope John Paul II (1978-2005) reshaped the Catholic Church's understanding of the just war theory. …