Catholic Teaching on Peace


The Catholic Church, since it was founded by Our Lord over 2000 years ago, has always been an advocate for peace in the world. However, in the Catholic tradition, peace is not merely the absence of war and conflict; rather, it is the ordering of human nature according to the eternal law of God. The Compendium of the Social Doctrine of the Church states,
“Before being God’s gift to man and a human project in conformity with the divine plan, peace is in the first place a basic attribute of God: ‘The Lord is peace’ (Jdg 6:24). Creation, which is a reflection of the divine glory, aspires to peace. God created all that exists, and all of creation forms a harmonious whole that is good in its every part. Peace is founded on the primary relationship that exists between every human being and God himself, a relationship marked by righteousness. Following upon the voluntary act by which man altered the divine order, the world experienced the shedding of blood and division. Violence made its appearance in interpersonal relationships and in social relationships. Peace and violence cannot dwell together, and where there is violence, God cannot be present.”-Compendium of the Social Doctrine of the Church, 488
There are many Church documents and papal encyclicals and messages concerning the promotion of peace in the world. See the resource section below for links to where many of these documents can be read online.

Just War Theory

For many centuries, the Church’s teaching on peace and war has been shaped by the just war theory. Just War Theory is the philosophical doctrine which states that war should be avoided at all costs, but if the correct conditions are present, then a war can be justified. The two pioneers of this theory were Saint Augustine and Saint Thomas Aquinas. Saint Augustine wrote that, “The commandment forbidding killing was not broken by those who have waged wars on the authority of God.” Saint Thomas went further by actually laying out three conditions of a just war. He stated that a war needed to be fought for a just case, waged by a proper authority, and done with the right intentions (For more information on this, see the Summa Theologica II-II, Q. 40). In summary of Just War Theory, the Catechism of the Catholic Church states:

“At one and the same time:

  • The damage inflicted by the aggressor on the nation or community of nations must be lasting, grave, and certain;
  • All other means of putting an end to it must have been shown to be impractical or ineffective;
  • There must be serious prospects of success;
  • The use of arms must not produce evils and disorders graver than the evil to be eliminated. The power of modern means of destruction weighs very heavily in evaluating this condition.”

-Catechsim of the Catholic Church, 2309


Professor Joseph Capizzi on Just War Theory