How has the gospel of the knowledge of God spread throughout the world?

 

Altars of idols have been overthrown. Knowledge of God has been implanted. The consubstantial Trinity, the uncreated Godhead is worshipped, one true God, Creator and Lord of all. Virtue is practiced. Hope of the resurrection has been granted through the resurrection of Christ. The demons tremble at the men who were formerly in their power. Yes, and most wonderful of all is that all these things were successfully brought about through a cross and suffering and death. The Gospel of the knowledge of God has been preached to the whole world and has put the adversaries to flight not by war and arms and camps. Rather, it was a few unarmed, poor, unlettered, persecuted, tormented, done-to-death men, who, by preaching the One who had died crucified in the flesh, prevailed over the wise and powerful, because the almighty power of the Crucified was with them. That death which was once so terrible has been defeated and He who was once despised and hated is now preferred before life. These are the successes consequent upon the advent of Christ; these are the signs of His power... O Christ, O wisdom and power and Word of God, and God almighty! What should we resourceless people give you in return for all things? For all things are Yours and You ask nothing of us but that we be saved. And even this You have given us, and by Your ineffable goodness You are gracious to those who accept it. 

- John of Damascus An Exact Exposition of the Orthodox Faith, 4.4