The son of Constantius, Constantine, became emperor in 307. He was in doubt between the two religions; he saw that Christianity made people good, and yet he could not quite leave off believing in the heathen gods, and was afraid of neglecting them. As he was passing the Alps to put down a very powerful and cruel tyrant, who had made himself master of Italy, he and all his army suddenly beheld in the sky, at mid-day, a bright light shaped like a cross, and in glorious letters round it, the Latin words meaning, "In this sign thou shalt conquer." This wonderful sight made Constantine believe that the cross was truly the sign of salvation, and that He who could show such marvels in heaven, must be the true God. He set the cross on his standards instead of the Roman Eagle; and such great victories were vouchsafed to him, that by-and-by he became the only emperor, and put down all his enemies.

He was not as yet baptized, but he was a hearty believer, and he tried in everything to make the Church prosperous, and to govern by Christian rules. From that time all the chief powers of this world have professed to be Christian, and the Church has been owned as the great means appointed by God of leading His people to Himself. Constantine's mother, Helena, though in her eightieth year, set off to the ruins of Jerusalem to try to trace out the places hallowed by our Saviour's suffering. All was waste and desolate, and no one lived there save a few very poor Jews and Christians in wretched huts. The latter had never lost the memory of the places where the holy events of the Passion had taken place; and the empress set men to dig among the ruins on Mount Calvary, till she found the Holy Sepulchre, and not far from it, three crosses, and the nails belonging to them. She built a most beautiful church, so large as to cover the whole of Golgotha. The sepulchre itself formed a round vault within, crusted over with marble, and lighted with silver lamps. The true Cross was kept in the church, but the nails she brought home as the most precious gift she could carry to her son. She also beautified and made into a church the cave of the Nativity at Bethlehem, and she built another church on Mount Carmel in memory of Elijah. From her time it became a habit with devout persons to go on pilgrimage, to worship at the holy tomb and in the Cave of Bethlehem; and a new city of Jerusalem rose upon the ruins of the old one, though, of course, without a Temple. Rome was so fall of the tokens of heathenism, that Constantine feared that his court would never be heartily Christian till he took it to a fresh place; so he resolved to build a new capital city for his empire. This was the city called after him, Constantinople, the city of Constantine, on the banks of the Bosphorus, just where Europe and Asia nearly meet. The chief building there was a most beautiful church, dedicated to the holy Wisdom of God, and named in Greek St. Sophia. The Bishop there was termed the Patriarch of Constantinople. There were already five patriarchs, or great Father Bishops, to rule over divisions of the Church at Jerusalem, Antioch, Alexandria, and Rome. The Patriarch of Rome was called the Pope. All was peace and prosperity, and the Christians were so much at their ease, that some finding that they missed the life of hardness, which they used to think a great blessing, went apart from men, and lived in caves, quite alone, working hard for very scanty food, and praying constantly. These were called hermits. But there soon were troubles enough rising up within the Church herself, for a man named Arius, a priest at Alexandria, began wickedly to teach that our blessed Lord was not from all eternity, nor equal with God the Father. So many persons were led away by this blasphemous heresy, (which means a denial of the faith,) that it was resolved to call together as many Bishops as possible from the entire Church, to hold a General Council, and declare the truth.