The Catholic Defender: The birth of Christ is the birth of peace to the Church, From a sermon by Pope Saint Leo the Great

They then who are born not of blood nor of the will of the flesh nor of the will of man but of God John 1:13, must offer to the Father the unanimity of peace-loving sons, and all the members of adoption must meet in the First-begotten of the new creation, Who came to do not His own Will but His that sent Him; inasmuch as the Father in His gracious favour has adopted as His heirs not those that are discordant nor those that are unlike Him, but those that are in feeling and affection one.

They that are re-modelled after one pattern must have a spirit like the model.

The birthday of the Lord is the birthday of peace: for thus says the Apostle, He is our peace, who made both one ; since whether we be Jew or Gentile, through Him we have access in one Spirit to the Father.

And it was this in particular that He taught His disciples before the day of His passion which He had of His own free-will fore-ordained, saying, My peace I give unto you, My peace I leave for you John 14:27; and lest under the general term the character of His peace should escape notice, He added, not as the world give I unto you Ib .

The world, He says, has its friendships, and brings many that are apart into loving harmony.

There are also minds which are equal in vices., and similarity of desires produces equality of affection.

And if any are perchance to be found who are not pleased with what is mean and dishonourable, and who exclude from the terms of their connection unlawful compacts, yet even such if they be either Jews, heretics or heathens ,

belong not to God's friendship but to this world's peace.

But the peace of the spiritual and of Catholics coming down from above and leading upwards refuses to hold communion with the lovers of the world, resists all obstacles and flies from pernicious pleasures to true joys, as the Lord says: Where your treasure is, there will your heart be also Matthew 6:21: that is, if what you love is below you will descend to the lowest depth: if what you love is above, you will reach the topmost height: there may the Spirit of peace lead and bring us, whose wishes and feeling are at one, and who are of one mind in faith and hope and in charity: since as many as are led by the Spirit of God these are sons of God Romans 8:14 Who reigns with the Son and Holy Spirit for ever and ever. Amen.