St. John XXIII prayed that God would transform our hearts into "witnesses of truth, justice and brotherly love."
Peace on earth has always been elusive and will remain so until Jesus comes again. However, that does not mean we should stop working for unity and peace, doing what we can to allow Jesus’ kingdom to reign on earth.
St. John XXIII greatly desired peace, writing an encyclical on the matter entitled, Pacem in Terris (Peace on Earth).
Here is a prayer he composed near the end of the encyclical that expresses his desire for peace and asks God to break down the barriers of division, opening up the way to authentic peace.
Let us, then, pray with all fervor for this peace which our divine Redeemer came to bring us. May He banish from the souls of men whatever might endanger peace. May He transform all men into witnesses of truth, justice and brotherly love. May He illumine with His light the minds of rulers, so that, besides caring for the proper material welfare of their peoples, they may also guarantee them the fairest gift of peace.Finally, may Christ inflame the desires of all men to break through the barriers which divide them, to strengthen the bonds of mutual love, to learn to understand one another, and to pardon those who have done them wrong. Through His power and inspiration may all peoples welcome each other to their hearts as brothers, and may the peace they long for ever flower and ever reign among them.