God's Providence made ready the Roman empire to spread the Gospel

Pope St. Leo the Great, Sermon 82, 5th century: “But that the result of this unspeakable Grace [of the Incarnation] might be spread abroad throughout the world, God's Providence made ready the Roman empire, whose growth has reached such limits that the whole multitude of nations are brought into close connection. For the Divinely-planned work particularly required that many kingdoms should be leagued together under one empire, so that the preaching of the world might quickly reach to all people, when they were held beneath the rule of one state… For when the twelve Apostles, after receiving through the Holy Ghost the power of speaking with all tongues, had distributed the world into parts among themselves, and undertaken to instruct it in the Gospel, the most blessed Peter, chief of the Apostolic band, was appointed to the citadel of the Roman empire, that the light of Truth which was being displayed for the salvation of all the nations, might spread itself more effectively throughout the body of the world from the head itself.”