I found this... it seems that historians believed he professed a faith in Christ... Scholars debate whether Constantine adopted his mother St. Helena's Christianity in his youth, or whether he adopted it gradually over the course of his life.[20] Constantine was over 40 when he finally declared himself a Christian.[21] Writing to Christians, Constantine made clear that he believed he owed his successes to the protection of the Christian High God alone.[22] Throughout his rule, Constantine supported the Church financially, built various basilicas, granted privileges (e.g. exemption from certain taxes) to clergy, promoted Christians to high ranking offices, and returned property confiscated during the Great Persecution of Diocletian.[23] His most famous building projects include the Church of the Holy Sepulchre and Old Saint Peter's Basilica.The reign of Constantine established a precedent for the position of the Christian Emperor in the Church; Constantine considered himself responsible to God for the spiritual health of his subjects, and thus he had a duty to maintain orthodoxy.[24] For Constantine, the emperor did not decide doctrine - that was the responsibility of the bishops - rather his role was to enforce doctrine, root out heresy, and uphold ecclesiastical unity.[25] The emperor ensured that God was properly worshipped in his empire; what proper worship consisted of was for the Church to determine.[26]^ R. Gerberding and J. H. Moran Cruz, Medieval Worlds (New York: Houghton Mifflin Company, 2004) p. 55 ^ Peter Brown, The Rise of Christendom 2nd edition (Oxford, Blackwell Publishing, 2003) p. 61 ^ R. Gerberding and J. H. Moran Cruz, Medieval Worlds (New York: Houghton Mifflin Company, 2004) pp. 55-56