Why do myths abound? Yes, I mean myths. History is full of myths, tales in where we make mere men as gods and heroes. Molehills of moments blown into mountains of false memories.
How many of us truly know that George Washington did not really cut down the cherry tree, or that Helen Keller was a communist, that the first Thanksgiving with the Pilgrims was an American fabrication, that Martin Luther was an anti-semite and John Calvin a murderer? We paint our heroes with the broad stroke of perfection, and the same goes for Constantine the Great, the first "Christian" Emperor. Some books will have you believe that Constantine was used by God, he was a "Saint." And in this they need to. The central doctrine of Christendom is the Trinity, which was brought about through no small measure of help by Constantine the Great. If Constantine's portrait was less than Christian, then the next logical step is to wonder what problems there are with the Trinity doctrine. So, the question put forward is: Is Constantine sinner or Saint?

It is significant, for instance, not that the pagan gods and their legends survived for a few years on Constantine's coinage but that they disappeared so quickly:  the last of them, the relatively inoffensive "Unconquered Sun" had been eliminated within little over a decade after the defeat of Maxentius (Encyclopedia Britannica, 1979, Constantine the Great, Vol. 5, p.71)

“Constantine’s nephew Julian speaks of Constantine’s connection with a special cult of Helios.  From a familiar obverse on coins of Constantine, representing the sun-god with the inscription SOLI. INVICTI. COMITI, we deduce that the personification of the sun as Mithras is here implied. Anyone who has dealt with ancient coins knows that out of five Constantinian pieces probably four will bear this obverse, so that there is a high probability that this device was retained until the Emporer’s death…But the coins with unequivocal Christian emblems which he is said to have struck are yet to be found” The Age of Constantine the Great, 1949, Jacob Burckhardt, p.293

          Nor was the visit to Rome a success. Constantine's refusal to take part in a
                 pagan procession offended the Romans; and when he left after a short visit, it
                 was never to return. (Encyclopedia Britannica, 1979, Constantine the Great,
                 Vol. 5, p.71)
               the accusation that his [Constantine’s] generosity was only made possible by
                 his looting of the treasures of the pagan temples (Encyclopedia Britannica,
                 1979, Constantine the Great, Vol. 5, p.71)

"Although Constantine attributed his success to the divine message that he beleived he had read in the skies before the battle at the Milvian Bridge in 312, he could not officially--and privately, it seems, did not-abandon paganism at once." Encyclopedia Americana 2000

"However, until his preparations for his final campaign by 323, he did not abandon his allegiance to the Sun god, even though he regarded himself as a servant of the Christian God... Constantine's public image remained - the Sun god was the emperor's 'companion.' The liberation of Rome was attributed to the Sun on a medallion struck at the time." The Rise of Christianity, W.H.C. Frend, p.484

 Constantine’s Conversion and Genuineness of Faith Assessment. The reign of Constantine must be interpreted against the background of his clear and unambiguous personal commitment to Christianity. (Encyclopedia Britannica, 1979, Constantine the Great, Vol. 5, p.71)

"Some things have been established with reasonable certainty: Constantine was no intellectual giant; he took himself very seriously with regard to what he considered his mission to promote Christianity; and lacking more than one of the Christian virtues, he was on occasion cruel, ruthless, and even inhumane."  Encyclopedia Americana 2000

"Constantine was almost certainly a Mithraic, and his triumphal arch, built after his 'conversion', testifies to the Sun-god, or 'unconquered sun'. Many Christians did not make a clear distinction between this sun-cult and their own. They referred to Christ 'driving his chariot across the sky'; they held their services on Sunday, knelt towards the East and had their nativity feast on 25 December, the birthday of the sun at the winter solstice. During the later pagan revival under the Emperor Julian many Christian found it easy to apostacize because of this confusion; the Bishop of Troy told Julian he had always secretely prayed to the sun. Constantine never abandoned sun-worship and kept the sun on his coins. He made Sunday into a day of rest, closing the law courts and forbidding all work except agricultural labour. In his new city of Constantinople, he set up a statue of the sun-god, bearing his own features, in the Forum; and another of the mother-Goddess Cybele, though she was presented in a posture of Christian prayer.
Constantine's motives were probably confused. He was an exceptionally superstitious man, and he no doubt shared the view, popular among professinal soldiers, that all religous cults should be respected, to appease their respective gods....Vain and superstitious, Constantine may have embraced Chrstianity because it suited his personal interests, and his growing megalomania.... His own role was not wholly removed from that of the pagan God-emperor - as witness the colossal heads and statues of himself with which he littered his empire...How could the Christian Church, apparently quite willingly, accomodate this weird megalomaniac in its theocratic system?" A History of Christianity "Paul Johnson pp. 67, 68

"Few of the essential elements of Christian belief interested Constantine very much-neither God's mercy nor man's sinfulness, neither damnation nor salvation, neither brotherly love nor, needless to say, humility. Ardent in his convictions, he remained nevertheless oblivious to their moral implications. Modern historians have been bothered by this;" [Constantine by Ramsay MacMullen, p. 239]
This is the same man that even some of his time was considered analogous to Christ. [cf. pp 176, 177]

What about the famous council of Nicaea:
"Constantine, who treated religious questions solely from a political point of view, assured unanimity by banishing all the bishops who would not sign the new profession of faith. In this way unity was achieved/ 'It was altogether unheardof that a universal creed should be instituted solely on the authority of the emperor, who as a catechumen was not even admitted to the mystery of the Eucharist and was totally unempowered to rule on the highest mysteries of the faith. Not a single bishop said a single word against this monstrous thing." [Walter Nigg, The Heretics, Heresy Throught the Ages, p127]

          "When he [Constantius] died at York on 25 July 305 the soldiers proclaimed
                 his son Constantine as emperor. Constantine, like his father, worshipped
                 the Unconquered Sun [page 122]... "The conversion of Constantine marks a
                 turning-point in the history of the Church and of Europe." ... "But if his
                 conversion should not be interpreted as an inward experience of grace,
                 neither was it a cynical act of Machiavellian cunning. It was a military
                 matter. His comprehension of Christian doctrine was never very clear,
                 but he was sure that victory in battle lay in the gift of the God of the
                 Christians....He was not baptized until he lay dying in 337, but this implies no
                 doubt about his Christian belief. It was common at this time (and continued so
                 until about A.D. 400) to postpone baptism to the end of one's life, especially if
                 one's duty as an official included torture and execution of criminals. Part of the
                 reason for postponement lay in the seriousness with which the responsibilities
                 of baptism were taken. Constantine favoured Christianity among the many
                 religions of his subjects, but did not make it the official or 'established' religion
                of the empire." (The Early Church, Chadwick, Henry. p 122,125,127)

"Constantine was a hot-blooded man. He was wise to avoid being baptized while there were still so many sins of passion that he might yet commit." [Rubenstein, p. 49]
"The last years of C(onstantine)'s life saw an approach to the Arian position: he was baptized by a bishop with Arian tendencies shortly before his death near Nicomedia in May 337." [Encyclopedia of the Early Church, p. 193]
"...it may be that the Church refused him the sacrament because of his manner of life. Certainly it was not his piety which made him a Christian." [A History of Christianity, Paul Johnson, 1928, p.68]

 The fact that Constantine murdered his son is no proof that Constantine was not a Christian.
We are not told why Constantine murdered his son. Anti-Trinitarians are basically trying to trash the genuineness of Constantine's Christianity and his involvement in the Nicene creed. Britannica notes Constantine putting his son to death, but says it was for reasons unknown. What if his son committed murder himself, and Constantine, just like the USA today, executed him, being head of state! The fact that Constantine killed his own son, could be taken, should the facts ever be known, as a sign of his impartial intolerance of sin even in his own family! In this case the murder of his son could be viewed as an act of righteous faith!

"At around the same time, the emporer tried the apparently related case of a young Roman aristocrat, Ceionius Rufius Albinus, who was accused of adultery and black magic, convicted him, and sent him onto permanent exile." [When Jesus Became God, Rubenstein, p.91]

"In July he arrived in Rome, only to be confronted by his mother, the devout Helena, who had become a symbol of Christian piety throughout the empire. Dressed in mourning, she accused him of executing her grandson hastily on false evidence. Evidently, she offered evidence that Fausta had masterminded the plot in order to rid her sons of the leading rival for the succession. One can only imagine the scene that must have ensued between Constantine and his wife, but the outcome is well attested. Fausta visited the steam room of the baths at the imperial palace and asphyxiated in the overheated air. She is generally believed to have suicided to avoid the executioner, but some have pictured her being hurled into the scalding steam by Constantine's agents, the doors held fast against her escape.
Not long after this, Bishop Hosius requested permission to leave Constantine's court...one suspects that it was a response to the horrors the bishop had witnessed." [Rubenstein, pp. 91,92]

"To pass for a Christian would, indeed, have been a great presumption on his part. Not long after the Council of Nicaea he suddenly had Crispus, his excellent Son by his first marraige and a pupil of Lactantius, put to death at Pola in Istria (326), and soon thereafter he had his wife Fausta, daughter of Maximian, drowned in her bath. The 11 year old Licinianus was also murdered, apparently at the same time as Crispus....that the horror was not merely a family affair but possessed political implications can be deduced from the fact that Licinianus was included among the victims. [The Age of Constantine the Great,  pp.283,284, Burckhardt]

"In modern-day terms, Constantine could hardly be considered much of a Christian. As an example, he never relinguished his title Pontifex Maximus. This was the title given to him as the head of the state pagan cult, which was either Mithraism or Sol Invictus, two distinct but similar religions. In addition, the coinage of his reign continued to depict the Sun God [Sol Invictus]. Finally, it is reported that he personally murdured one of his own sons, had his second wife drowned, had his nephew and brother-in-law killed after he had guaranteed safe passage, etc. However, during all of this he sponsored Christianity because it had been useful to him in winnig a decisive battle."
[The Christian Conspiracy, p. 58, Dr. L.D. Moore]

A rotten tree does indeed bear rotten fruit. Matthew 7:17

Bible.ca: Your article is riddled with both errors and mistakes. Nothing you wrote
refuted the facts of history.
Your sources are insignificant and invalid.

Britannica is the most reliable source of historical information in the
world. Take a look at the bibliography.
Britannica is not ONE SOURCE it is the consensuses of world opinion.
Look up Christmas and its pagan origin. It is dead on! Bible.ca

"The reason why Christmas came to be celebrated on December 25 remains uncertain, but most probably the reason is that early Christians wished the date to coincide with the pagan Roman festival marking the "birthday of the unconquered sun" (natalis solis invicti); this festival celebrated the winter solstice, when the days again begin to lengthen and the sun begins to climb higher in the sky."