it happened on the way to the forum: christogram or eastern-pivot

Born into the power-sharing arrangement that Diocletian established and the attendant civil wars that erupted across the Empire whenever one leader sought to recall the devolved governance, which even Diocletian witnessed in his retirement in Dalmatia—his careful planning collapsing despite his gracious bowing-out—though refusing entries to return and put an end to the in-fighting and poisonous ambition for more than a good regional share of the world, Constantine the Great, fore-father of the Holy Roman and Byzantine Empires and revered as a saint in the Eastern tradition is a character of indubitable significance but forever escaping true comprehension.
Stripping away every other accomp- lishment and monument and joining him at the beginnings of his career, Constantine was a regional leader, an Augustus with his power-base centred in Trier. Dissatisfied only holding imperium over the Germania and Gaul, Constantine also tried to consolidate his holdings, launching offensives against his imperial colleagues. Whether his campaigns were carefully calculated in the name of self-interest or as a defender of the faith is a matter of much debate and ultimately the answer is something as private and inaccessible as belief and credulity. Perhaps recognising the political capital vested within the growing Christian population was more valuable that simply using these vaguely treasonous up-standing citizens as convenient scapegoats or perhaps out of genuine concern to stop the persecutions, Constantine issued the Edict of Milan that legitimised Christianity and banned their mistreatment—which effectively undid the terror visited on the community by Diocletian—the torture, the marginalising, the confiscation of property.
Constantine also famously raised campaigns against these pretenders but not exactly under the ægis of the Cross and rather by a vision communicated to him to him that his troops ought to bear the sign Chi-Rho (the Greek ligature of the letters Χ and Ρ, ☧, which appeared as marginalia short-hand and the equivalent of Latin NB, nota bene—good or important, long before it was understood as a monogram of Jesus), who were proponents for the return of Christian oppression. Whether their advocacy was rooted in slighted patrons, pagans that were remiss to have their abated riches taken back, or out of genuine devotion to the elder pantheon, Constantine's co-emperors were felled. Either out of a preponderance of caution or a demurring sense of being non-committal, however, the Triumphal Arch erected to immoralise his conquests bore no mention of the High God of the Christians and there was little talk of Christ and God, yet. Constantine’s sainted mother, Helen, was dispatched on a long good-will tour, making a pilgrimage to the Holy Land with a large entourage and collecting a lot of relics along the way. Mother and son commissioned the Church of the Holy Sepulcher and the original St. Peter’s Basilica in Rome, on the spot where the apostle was martyred. Despite his building initiatives which included many public facilities and infrastructure projects aside from the churches, Constantine remained rather silent on the matter of faith and proselytising but was always troubled by the squabbling within the hierarchy of the emerging Church.
Seemingly wanting to present a united front rather than risk a tradition that would plunge just as easily into sectarianism, Constantine began to directly engage doctrinal controversies. First, there was emergent issue of what to do about the Christians who had been pragmatic during the purges and obliged by making sacrifices to the pagan gods in order to escape punishment, and then there was the matter of the Arian schism (named for the priest, Arius of Alexandria) concerning the nature of Christ—whether He, as begotten, could still be considered divine or whether the Trinity was just different aspects of the self-same God. Constantine seemed to think that this was a rather petty question and certainly not worth excommunication and disunity. To let the opposing schools of thought finally hash out their differences, Constantine called together a meeting of the bishops and although the winning side and compromised reached was not exactly the outcome that the Emperor was backing—and Constantine could of course been more dictatorial as Pontifex Maximus had he wanted and just decided matters for himself—he respected the group’s decision. A bit naïve about Church politics and the volatility of opposing camps in matters of faith with the Arianists and non-Arianists certainty did not feeling that their squabble was trivial, Constantine was quite nonplussed that once debate was over, the two sides did not come together and all disagreements did not suddenly evaporate. So to try to settle matters once and for all, the Emperor called for a bigger council that represented a much broader swath of the faithful and convened the first Ecumenical Council in Nicaea, with bishops from all across the known world. Over the weeks, the nature of the Son of God was fixed—though as an even more confusing answer than the question posed, the calculus for determining the dates of moveable feasts like Eastertide, who was eligible for baptisms, and a host of other questions. With the matter appearing tidily resolved, Constantine could embark on other matters of state, including creating for himself a new capital. The City of Rome itself know abandoned as a sort centre emeritus, and all other metropolitan candidates, like Milan or Trier or Salona, fell short in one way or another. Constantine therefore decided to build up a fishing village on the Bosporus, styling it New Rome.
That name never caught on and the great capital was referred to as Constantinople (the city of Constantine) and ultimately İstanbul, derived from the accusative case of “the City.” Constantine did some momentous things during a career that spanned three decades and founding institutions that would go on shaping the world forever more, but the genuineness of his belief, and Whom exactly was his champion, remains mysterious. His ambitions and general deportment—including executing his wife and son for the sake of inheritance—was not very Christian, plus after all those efforts at reform and elevating the religion, Constantine himself was seemingly a death-bed convert, albeit that it was an efficient use of a baptismal since it is cumulative and the dying Emperor did not get the chance to commit any more egregious acts afterwards. Some blame the spread of Christianity for the downfall of the Empire and by extension, civilisation, and say the Church only saved the most Byzantine and corruptible elements of Roman bureaucracy. The great Emperor also had his failings, including monetary reform that pared away inflation but only benefited the wealthy and created class disparity with little mobility, poor succession-planning that led to the resumption of the civil wars that engulfed the Empire, a rift in the Church that only expanded in manifold ways, and a senseless war with Persia—ostensibly to protect the Christian population of Armenia, that benefited no one as one of his last official acts. Whatever the fundamental motivations—and this is an important question, the so-called Donation of Constantine is all around us to this day.