Constantine
Constantine was the first emperor to stop the persecution of Christians and to legalise Christianity, along with all other religions/cults in the Roman Empire. In February 313, he met with Licinius in Milan and developed the Edict of Milan, which stated that Christians should be allowed to follow their faith without oppression.[232] This removed penalties for professing Christianity, under which many had been martyred previously, and it returned confiscated Church property. The edict protected all religions from persecution, not only Christianity, allowing anyone to worship any deity that they chose. A similar edict had been issued in 311 by Galerius, senior emperor of the Tetrarchy, which granted Christians the right to practise their religion but did not restore any property to them.[233] The Edict of Milan included several clauses which stated that all confiscated churches would be returned, as well as other provisions for previously persecuted Christians. Some scholars think that Helena adopted Christianity as an adult, and according to Eusebius she was converted by Constantine,[234] but other historians debate whether Constantine adopted his mother Helena's Christianity in his youth or whether he adopted it gradually over the course of his life.[235]
Pope Sylvester I and Emperor Constantine
Constantine possibly retained the title of pontifex maximus which emperors bore as heads of the ancient Roman religion until Gratian renounced the title.[236][237] According to Christian writers, Constantine was over 40 years old when he finally declared himself a Christian, making it clear that he owed his successes only to the protection of the Christian God.[238] Despite these declarations of being a Christian, he waited to be baptised until on his deathbed, believing that the baptism would release him of any sins he committed in the course of carrying out his policies while emperor.[239] He supported the Church financially, built basilicas, granted privileges to clergy (such as exemption from certain taxes), promoted Christians to high office, and returned property confiscated during the long period of persecution.[240] His most famous building projects include the Church of the Holy Sepulchre and Old St. Peter's Basilica. In constructing the Old St. Peter's Basilica, Constantine went to great lengths to erect the basilica on top of St. Peter's resting place, so much so that it even affected the design of the basilica, including the challenge of erecting it on the hill where St. Peter rested, making its complete construction time over 30 years from the date Constantine ordered it to be built.
Constantine might not have patronised Christianity alone. A triumphal arch was built in 315 to celebrate his victory in the Battle of the Milvian Bridge which was decorated with images of the goddess Victoria, and sacrifices were made to pagan gods at its dedication, including Apollo, Diana, and Hercules. Absent from the arch are any depictions of Christian symbolism. However, the arch was commissioned by the Senate, so the absence of Christian symbols may reflect the role of the Curia at the time as a pagan redoubt.[241]
In 321, he legislated that the venerable Sunday should be a day of rest for all citizens.[242] In 323, he issued a decree banning Christians from participating in state sacrifices.[243] After the pagan gods had disappeared from his coinage, Christian symbols appeared as Constantine's attributes, the chi rho between his hands or on his labarum,[244] as well on the coinage.[245] The reign of Constantine established a precedent for the emperor to have great influence and authority in the early Christian councils, most notably the dispute over Arianism. Constantine disliked the risks to societal stability that religious disputes and controversies brought with them, preferring to establish an orthodoxy.[246] His influence over the Church councils was to enforce doctrine, root out heresy, and uphold ecclesiastical unity; the Church's role was to determine proper worship, doctrines, and dogma.[247]
North African bishops struggled with Christian bishops who had been ordained by Donatus in opposition to Caecilian from 313 to 316. The African bishops could not come to terms, and the Donatists asked Constantine to act as a judge in the dispute. Three regional Church councils and another trial before Constantine all ruled against Donatus and the Donatism movement in North Africa. In 317, Constantine issued an edict to confiscate Donatist church property and to send Donatist clergy into exile.[248] More significantly, in 325 he summoned the First Council of Nicaea, most known for its dealing with Arianism and for instituting the Nicene Creed.[249] He enforced the council's prohibition against celebrating the Lord's Supper on the day before the Jewish Passover, which marked a definite break of Christianity from the Judaic tradition. From then on, the solar Julian calendar was given precedence over the lunisolar Hebrew calendar among the Christian churches of the Roman Empire.[250]
Constantine made some new laws regarding the Jews; some of them were unfavourable towards Jews, although they were not harsher than those of his predecessors.[251] It was made illegal for Jews to seek converts or to attack other Jews who had converted to Christianity.[251] They were forbidden to own Christian slaves or to circumcise their slaves.[252][253] On the other hand, Jewish clergy were given the same exemptions as Christian clergy.[251]