Constantine I (272-337 AD) was emperor of at least portions of the Roman Empire from 306-337 AD, and is lauded in Christianity for convoking the First Council of Nicaea (325 AD). This brief biographical section will focus on two events in his life:
Beginning with his murder of his own son Crispus (May-June 326 AD), and his wife Fausta (July 326 AD), author Michael Grant writes:
Constantine the Great - The Man and His Times, Chapter 6, pg. 109
Eutropius declared that Constantine was responsible for many murders of his 'friends', and this was unmistakably true. There was a long list of his victims. It is no use trying to excuse this in the light of an ancient civilization that had different ideals from ours, and so on, and by pointing out that other leaders such as Diocletian and especially Licinius had also committed assassinations. For Constantine's behavior is inexcusable by any standards, and casts a blot on his reputation. Being an absolute autocrat, he believed that he could kill anyone.
Constantine the Great - The Man and His Times, Chapter 6, pg. 114
So Constantine murdered both his eldest son and his wife. The Epitome of Aurelius Victor was surely right in linking the two crimes, and modern writers who regard them as unconnected are wrong. Even if, looking at it as cold-bloodedly as we can, we are able, with difficulty, to summon up the ability to defend, or at least excuse, one or other of the two executions as justified on political, national grounds, it is impossible to justify both of them. And, indeed, neither the one nor the other can really be justified at all. It could well be argued that they are the deeds of a tyrant whose feelings had got completely out of hand.
Note that both murders took place in the Summer of 326 AD, over a decade after Constantine's supposed vision at the Battle of the Milvian Bridge (312 AD), in which he claimed he saw a vision of a cross, and an inscription which said, "In this sign, conquer". The date of 326 AD also places the killings after the Council of Nicaea, for which Constantine is praised.
In addition to his son and wife, it is also worth noting that in this same year, Constantine murdered the 11 year-old Licinius II (315-326 AD), who was the son of rival Emperor Licinius (265-325 AD), and also Constantine's own half-nephew.
Concerning the baptism of Constantine, Grant writes:
Constantine the Great - The Man and His Times, Chapter 11, pg. 211
In 337 AD, at the very end of his life when he knew he was about to die, Constantine had himself baptized in a village near Nicomedia by its bishop Eusebius (not the ecclesiastical historian Eusebius of Caesarea). Before baptism, Constantine was required, theoretically, to spend a period as a catechumen, a convert under instruction. The Synod of Elvira had fixed a minimum of two years for this process, but it was no doubt waived in favor of Constantine.
Constantine the Great - The Man and His Times, Chapter 11, pg. 213
And so Constantine took off the purple robe of imperial power, was baptized naked (as was the custom) by Bishop Eusebius of Nicomedia, and put on the white vestment which Christian converts wore for a week after their baptism.
Catholics became uncomfortable about baptism at the hands of Eusebius of Nicomedia - who was practically an Arian - and invented a story that he was instead baptized by Pope Silvester I of Rome, which is repeated on the inscription upon the Egyptian obelisk in the Piazza di San Laterano. That this is entirely fictitious is one of the certainties in the long but obscure papacy of Silvester (314-35 AD). Constantine had evidently met Silvester, probably more than once, and had greatly enriched his Roman church, but it was not Silvester who baptized him. Nicomedia was not in Silvester's diocese, and, in any case, at the time of the emperor's baptism Silvester had already been dead for two years.
Significant above is the fact that he was baptized in 337 AD, shortly before he died, by Eusebius of Nicomedia, and that later, a story was invented in which he was baptized by Pope Sylvester I (285-335 AD) in Rome, many years before his death. This legend is attributed to the work entitled The Acts of Sylvester, which gives an entirely fictional account of Constantine's baptism, and is thought to date to the fourth or fifth century.
The fact that Constantine was baptized in Nicomedia at the end of his life is confirmed by the church historian Eusebius of Caesarea (265-339 AD), who personally knew Constantine, and wrote his Life of Constantine just a few years after Constantine's death:
Eusebius (265-339 AD) - Life of Constantine, Book 4
61 At first he experienced some slight bodily indisposition, which was soon followed by positive disease. In consequence of this he visited the hot baths of his own city; and thence proceeded to that which bore the name of his mother. Here he passed some time in the church of the martyrs, and offered up supplications and prayers to God. Being at length convinced that his life was drawing to a close, he felt the time had come at which he should seek purification from sins of his past career, firmly believing that whatever errors he had committed as a mortal man, his soul would be purified from them through the efficacy of the mystical words and the salutary waters of baptism.
Impressed with these thoughts, he poured forth his supplications and confessions to God, kneeling on the pavement in the church itself, in which he also now for the first time received the imposition of hands with prayer. After this he proceeded as far as the suburbs of Nicomedia, and there, having summoned the bishops to meet him, addressed them in the following words.
This is further confirmed by later church historian Sozomen (400-450 AD), who writes of the end of Constantine's life, "His malady, however, increased, and he went to Nicomedia, and was initiated into holy baptism in one of the suburbs of that city" (Sozomen - Ecclesiastical History, Book 2, Chapter 34).
This is also recorded in Jerome's (347-420 AD) Chronicon:
Jerome (347-420 AD) - Chronicon
279th Olympiad: Constantine, baptized by Eusebius of Nicomedia at the very end of his life, falls into the dogma of Arius, and from that time until now seizures of churches and discord of the whole world have followed. [337 AD]
The bishop of Nicomedia was Eusebius, who, as mentioned by Jerome and Michael Grant, seemed to be an Arian, who defended Arias and professed to believe in his doctrine:
Catholic Encyclopedia - Eusebius of Nicomedia
Arius, when he was condemned at Alexandria, by Alexander, bishop of that see, took refuge at Caæsarea, where he was well received by the famous apologist and historian Eusebius, and wrote to Eusebius of Nicomedia for support. The letter is preserved. In it the heretic explains his views clearly enough, and appeals to his correspondent as to a "fellow Lucianist". Eusebius put himself at the head of the party, and wrote many letters in support of Arius. One is preserved, addressed to Paulinius, Bishop of Tyre. We learn from it what Eusebius's doctrine was at this time: the Son he says is "not generated from the substance of the Father", but He is "other in nature and power"; He was created, and this is not inconsistent with his Sonship, for the wicked are called sons of God (Isaiah 1:2; Deuteronomy 32:18) and so are even the drops of dew (Job 38:28); He was begotten by God's free will. This is pure Arianism, borrowed from the letters of Arius himself, and possibly more definite than the doctrine of St. Lucian.
Even up to the end of his life, Eusebius of Nicomedia was a leader of the Arian movement, and was participating in a synod to condemn Athanasius (296-373 AD), one of the foremost defenders of the Deity of Christ at the time:
Dictionary of Christian Biographies, by Henry Wace - Eusebius of Nicomedia
In 340 the Eusebians held a synod at Antioch, at which Athanasius was once more condemned. In 341 (May) the council developed into the celebrated council in Encaeniis, held also at Antioch, at which, under the presidency of Eusebius or Placetus of Antioch, and with the assent and presence of Constantius, divers canons were passed, which are esteemed of authority by later oecumenical councils. These two councils are confounded and identified by Socrates and Sozomen.
The cruel injustice to which Athanasius was subjected by long exile is freely attributed to Eusebius, as its mainspring and constant instigator. Nevertheless the last thing we are told about Eusebius by Socrates is that he appealed from the council of Antioch to Julius, bp. of Rome, to give definite sentence as to Athanasius, but that before the sentence of Julius reached him, "immediately after the council broke up, breath went out of his body, and so he died," a.d. 342.
So, in light of the above information, two facts are clear:
The Eastern Orthodox Church, in spite of the above facts of history, abundantly praise Constantine and his mother Helena, calling them "Holy Equals-to-the-Apostles Emperor Constantine and his mother, Helen" (The Service Books of the Orthodox Church, St. Tikhon's Seminary Press, Appendix VI, May 21).
The Eastern Orthodox Church also sings a hymn entitled The Akathist to Saints Constantine and Helen, in which stanzas alternate between praises of Constantine, and his mother.
In the Akathist, Constantine is called "equal in honor to the Apostles of Christ" (Stanza 3), "equal in number to the divine Fathers" (Stanza 3), "deliverer of us who honor you" (Stanza 3), "Apostle of the Lord" (Stanza 5), "our divine nourishment" (Stanza 5), "through whom kings are granted wealth" (Stanza 5), "most-fervent follower of Christ" (Stanza 7), "wonder of the Angels" (Stanza 9), "broad giant who measures the heavens" (Stanza 9), "universal Atlas, who upholds the earth" (Stanza 9), "divine light of the world" (Stanza 11), "protector even at the hour of death" (Stanza 11), and "deliverer from the inexorable Judgment" (Stanza 11).
The level of emperor worship reflected in the above would be wildly inappropriate for any mere human being, even if they were virtuous, and lived an exemplary life. However, even worse, here it is for an immoral, murderous emperor, who continued killing even after becoming Christian, and after convoking the first Ecumenical Council. Constantine also seemed to tolerate Roman Paganism being associated with himself, as the Arch of Constantine in Rome, dedicated in 315 AD - 3 years after Constantine's supposed vision - has the Roman gods Apollo, Diana, Hercules, Silvanus, Sol, and Luna featured prominently on it. It is still standing today, meaning that obviously, Constantine never had it removed, nor the images of the false gods destroyed, on the monument dedicated to himself and his victory at the Battle of the Milvian Bridge.
Interestingly, the Akathist also calls Constantine "you who were baptized by Sylvester in Rome", reflecting the fraudulent narrative put forth by the Acts of Sylvester, wherein history is rewritten to move Constantine's baptism around 1,000 miles away from Nicomedia - where he was actually baptized - to Rome.
Therefore, the Eastern Orthodox Church errantly repeats a legend about Constantine's baptism which is known to be forged, and contradicts all of history, while simultaneously worshipping Constantine to the point of idolatry, and declaring him and his mother "equal to the Apostles" in their liturgical books.
Constantine the Great was an immoral Roman emperor, who potentially converted to Christianity. He was baptized by a bishop who appears to be Arian, shortly before his death. He does not deserve anywhere near the level of frankly idolatrous praise heaped upon him by the Eastern Orthodox.
The Acts of Sylvester also inspired the forged Donation of Constantine, which was used and built upon extensively by Popes of the Middle Ages to increase the temporal power of the Papacy (Pope Gregory VII - Dictatus Papae, 1090 AD, etc.), and recounts at length the fraudulent story of Constantine being baptized in Rome by Pope Sylvester I:
Donation of Constantine
And so, on the first day after receiving the mystery of the holy baptism, and after the cure of my body from the squalor of the leprosy, I recognized that there was no other God save the Father and the Son and the Holy Spirit; whom the most blessed Sylvester the pope doth preach; a trinity in one, a unity in three.
Therefore, both the Roman Catholic and Eastern Orthodox Churches have fallen prey to the forged Acts of Sylvester.