Eusebius, the author of traditions and legends of Christianity

In 312 The Roman Emperor Constantine accepted his own version of the Christian faith While he was preparing for another military campaign.  The story claims he had a vision of the cross against the sun, accompanied by the words, "In this sign, conquer."

It is said it was Constantine that made all religions legal and made Christianity the state religion. After this act it began to be corrupted by man centered thinking, and Greek philosophy.

“We grant both to Christians and to all men freedom to follow whatever religion each one wishes, in order that whatever divinity there is in the seat of heaven may be appeased and made propitious towards us and towards all who have been set under our power. . . . And since these same Christians are known to have possessed not only the places in which they had the habit of assembling but other property too which belongs by right to their body. . . you will order all this property. . . to be given back without any equivocation or dispute to all those same Christians.  (Quoted in Michael Walsh, The Triumph of the Meek: Why Early Christianity Succeeded (San Francisco: Harper & Row, 1986), 248.

Historians dispute whether Constantine's conversion to Christianity was genuine E.g., Henry Chadwick, The Early Church (Pelican Books, 1967, reprinted Penguin Books, 1990), 125-127; Edward Gibbon, The Decline and Fall of the Roman Empire, Great Books of the Western World ed. (Chicago: Encyclopedia Britannica, Inc.1952), 290. Although Eusebius recounts that in AD 312, Constantine saw a "vision" in which the sign of the cross was emblazoned across the sky surrounded by the words "In this, conquer," this "vision" was almost certainly apocryphal. See Ramsay MacMullen, Constantine (New York: Dial Press, 1969), 73.

Assole emperor. His first act (Soz. 1. 8) was to issue a proclamation in favor of the Christians (Soz. l.c.; V. C. 2. 24-, and 48). This was followed by many other acts in their favor,--building of churches,  

313 a.d. Edict of Constantine and Licinius for the restoration of the Church. In Lact. De M. P. c. 48, and also in Euseb. H. E. 10. 5 (Op. Const. ed. Migne, 105-110). The second edict of toleration. The first edict (Euseb. 8. 17; Lact. De M. P. 34) can hardly be classed among the "writings" of Constantine. This famous second edict grants full religious liberty to the Christians and restoration of their property. 

Constantine’s Vision

“Constantine called on him (God) with earnest prayer to reveal to him who he was, and stretch forth his right hand to help him in his present difficulties. And while he was thus praying with fervent entreaty, a most extraordinary sign appeared to him from heaven – something which it might have been hard to believe had the story been told by any other person. But since the victorious emperor himself long afterwards declared it to the writer of this history, when he was honored with his acquaintance and society, and confirmed his statement by an oath, who could hesitate to believe it, especially since other testimonies have established its truth? He said that about noon, when the day was already beginning to decline, he saw with his own eyes the sign of a cross of light in the heavens, above the sun, and bearing the inscription, “By this symbol you will conquer.” He was struck with amazement by the sight, and his whole army witnessed the miracle.

“He told his friend, Bishop Eusebius, the most eminent of early Church historians, that, after noon, as he was praying, he had a vision of a cross of light in the heavens bearing the inscription, .Conquer by this,. and that confirmation came in a dream in which God appeared to him with the same sign and commanded him to make a likeness of it and use it as a safeguard in all encounters with his enemies. How accurately Constantine remembered the experience we do not know, but Eusebius is usually discriminating in his evaluation of data, and he declares that he himself saw the standard which was made in response to the vision. a spear overlaid with gold, with a cross which was formed by a transverse bar and a wreath of gold and precious stones enclosing a monogram of the letters Chi and Rho for the name of Christ. The staff also had an embroidered cloth with the picture of Constantine and his children. Constantine was victor, the winning battle being at the Milvian Bridge, near Rome, and he therefore took possession of the capital. Presumably his faith in the efficacy of the Christian symbol was thus confirmed.” (“A History of Christianity,” by Kenneth Scott Latourette Vol. 1, pp. 3-494)

The Emperor constantly made use of this sign of salvation as a safeguard against every adverse and hostile power, and commanded that others similar to it should be carried at the head of all his armies.

Now we come to Eusebius, who is titled the first church historian (or some claim THE church historian).

Eusebius Around 315 he was elected bishop of Cæsarea, in Palestine, and found himself in the midst of a growing controversy of Arianism. He took the side of Arius, that Jesus was a creature. At the Council of Nicæa (325), he attempted to reconcile the opposing parties. Although he did not side with the homoousios doctrine of Athanasius (who was not a bishop), that held the full divinity and equality of Christ with the Father.  

When Constantine became the Emperor, fourteen years had already gone by since Emperor Galerius brought an end to the Christian persecutions. Many of the men who suffered for the name of Christ that survived the persecution were now representatives at the Council of Nicaea. In 325 (June 19-Aug. 25) the Council of Nicæa was held (cf. Euseb. V. C. 3. 6, and notes), and Constantine took an active part in its proceedings though he did not attend.  Eusibius eventually signed the formula approved at Nicæa, complying with Emperor Constantine who had convened the council for the new legal religion of Christianity.

Taking a historical view Eusebius explains the developing church and the relationship of Christianity with the Roman Empire and their leaders. Eusebius was Constantine’s ecclesiastical “biographer,” under Constantine’s leadership until 339 AD. Eusebius fully endorsed Constantine’s vision and his leadership, which tells us a whole lot about this man.  He was so supportive of Constantine, he called him Constantine the Great.

 Eusebius wrote an influential history of the church that is often referred to today. Many of the traditions of the apostles death came from Eusebius (i.e. Peter and Paul’s death, John boiled in oil). His view was certainly seen in some of his writings. He taught that the promises of scripture were for the gentiles while the curses were for the Jews, and that the church was the "true Israel.”

Eusebius must be questioned on at least some his writing of early history. He may not have corrupted all the early writings on every matter but certainly some. Unless one can use independent sources for the early writers apart from going through Eusibius we cannot accept his writings verbatim. Because of his loyalty and association with Constantine; he must be scrutinized. In fact, using Eusebius makes it far more difficult to speak out on Roman Catholics who makes use of these early writers he recorded. 

Eusebius the historian writes In CHAPTER XXXII: How Constantine received Instruction, and read the Sacred Scriptures.

These things were done shortly afterwards. But at the time above specified, being struck with amazement at the extraordinary vision, and resolving to worship no other God save Him who had appeared to him, he sent for those who were acquainted with the mysteries of His doctrines, and enquired who that God was, and what was intended by the sign of the vision he had seen. They affirmed that He was God, the only begotten Son of the one and only God: that the sign which had appeared was the symbol of immortality, (1) and the trophy of that victory over death which He had gained in time past when sojourning on earth. They taught him also the causes of His advent, and explained to him the true account of His incarnation. Thus he was instructed in these matters, and was impressed with wonder at the divine manifestation which had been presented to his sight.”

While Eusebius states this of Constantine, we find he believed the opposite. Constantine did not believe in the Trinity (ignoring the debates at the council of Niacea) he was later baptized believing Jesus was a creature.

It was Arius who believed Jesus was a creature. Arius, writing to Eusebius, Bishop of Nicodemia, when his father Ammonius was visiting the city Nicodemia, penned this, “how grievously the bishop attacks and persecutes us, and comes full tilt against us, so that he drives us from the city as atheists because we do not concur with him when he publicly preaches, ’God always, the Son always; at the same time the Father, at the same time the Son; the Son co-exists with God, unbegotten; He is ever begotten, He is not born by begetting; neither by thought nor by any moment in time does God precede the Son; God always, Son Always, the Son exists from God himself’…Arius’ view was “And before He was begotten or created or appointed or established, He did not exist; for He was not unbegotten. We are persecuted because we say the son had a beginning, but God is without beginning” (Letter to Eusibius 321 A.D. Theodoret. Bishop of Cyrus 423-458 H.E.I.v).

   Constantine was later won to the side of Arius by Eusebius of Nicodemia, the Emperors friend. Constantine then recalled Arius from exile sending him back to Alexandria. Receiving Eusebius of Nicodemia on his deathbed, Constantine was baptized an Arian (337 A.D) . Now supporting Arius' view, he rejected the Trinitarian view, and Constantine then disposed Athanasius and his followers

“Constantine began to wonder whether Arius had not been a heretic after all. But when the Emperor himself died, in the following year, he received the rites of baptism from his friend and counselor Eusebius, Bishop of Nicomedia, an Arian.

Constantius took theology more seriously than his father. He made his own inquiry into the paternity of Jesus, adopted the Arian view, and felt a moral obligation to enforce it upon all Christendom.” (THE STORY OF CIVILIZATION The Age of Faith Durant, Will, 1950)

Since Eusebius was an admirer of Constantine one should consider his accuracy in recording history as being so accurate as he is credited with.