The Edict of Milan went further than the previous edict of Serdica of Galerius in 311 and returned the confiscated property of the church. This edict made the empire officially neutral in terms of religious worship; he made neither traditional religions illegal nor Christianity the state religion, as he later did with the Edict of Thessalonica of 380. However, the Edict of Milan increased the existence of Christianity within the empire and affirmed the importance of religious worship for the welfare of the state.  The most influential people in the empire, especially senior officers, had not converted to Christianity and still participated in Rome`s traditional religions; Constantine`s reign showed at least a willingness to appease these factions. Roman coins, minted up to eight years after the battle, still bore images of Roman gods.  The monuments he first commissioned, such as the Arch of Constantine, contained no reference to Christianity.   After Galerius recognized Constantine as Caesar, the portrait of Constantine was brought to Rome as usual. Maxentius mocked the subject of the portrait as the son of one and lamented his own helplessness. Maxentius, jealous of Constantine`s authority, took the title of emperor on October 28, 306. Galerius refused to recognize him, but did not depose him. Galerius sent Severus against Maxentius, but during the campaign Severus` armies, previously under the command of Maxentius` father, Maximian, defected and Severus was captured and imprisoned.
 Maximian, awakened from his retirement by his son`s rebellion, went to Gaul at the end of 307 to consult Constantine. He offered Constantine to marry his daughter Fausta and raise her to the rank of Augustus. In return, Constantine would reaffirm the old family alliance between Maximian and Constantius and support Maxentius` cause in Italy. Constantine accepted and married Fausta in late summer 307 in Trier. Constantine gave Maxentius his meager support and offered Maxentius political recognition.  Constantine I (Flavius Valerius Constantinus) was Roman emperor from 306 to 337 AD and is known in history as Constantine the Great for his conversion to Christianity in 312 AD and his subsequent Christianization of the Roman Empire. His conversion was motivated in part by a vision he witnessed at the Battle of Milvian Bridge in Rome in 312 AD. As emperor, Constantine continued the usual practice of building monuments and basilicas (public buildings).
Their characteristic forms helped form the standard of the churches, with a nave and apses for the side altars. In Rome, Constantine built the first basilicas of St. Peter and St. John Lateran. His new imperial city of Constantinople was famous for its imperial architecture. In the years that followed, Constantine gradually consolidated his military superiority over his rivals in the ruined tetrarchy. In 313, he met Licinius in Milan to secure their alliance by marrying Licinius and Constantine`s half-sister, Constantia. During this meeting, the emperors agreed on the so-called Edict of Milan, which officially granted full tolerance to Christianity and all the religions of the empire.  The document had particular advantages for Christians in that it legalized their religion and granted them restitution of all property confiscated during Diocletian`s persecution.
It rejects earlier methods of religious coercion and uses only general terms to designate the divine sphere – “divinity” and “supreme divinity”, summa divinitas.  However, the conference was interrupted when Licinius received news that his rival Maximinus had crossed the Bosphorus and invaded European territory. Licinius gave up and eventually defeated Maximinus and took control of the entire eastern half of the Roman Empire. Relations between the two remaining emperors deteriorated when Constantine was assassinated by a figure whom Licinius wanted to elevate to the rank of Caesar;  Licinius, for his part, had the statues of Constantine destroyed at Emona.  In 314 or 316, the two Augusti clashed at the Battle of Cibalae, with Constantine victorious. They clashed again at the Battle of Mardia in 317 and agreed on a settlement in which Constantine`s sons, Crispus and Constantine II, and Licinius` son, Licinianus, were made Caesars.  Under this arrangement, Constantine ruled the dioceses of Pannonia and Macedonia and settled in Sirmium, from where he was able to wage war against the Goths and Sarmatians in 322 and against the Goths in 323, defeating and killing their leader Rausimod.  Constantine ruled the Roman Empire as sole emperor for much of his reign. Some scholars claim that its main purpose was to obtain unanimous consent and submission to its authority from all classes, and therefore chose Christianity to carry out its political propaganda, believing that it was the most appropriate religion that could suit imperial worship (see also Sol Invictus). Constantine`s adherence to Christianity was closely linked to his rise to power. He fought at the Battle of Milvian Bridge in the name of the Christian god after receiving instructions in a dream to paint the Christian monogram on the shields of his troops. This is the account of the Christian apologist Lactantius.
A slightly different version offered by Eusebius relates a vision that Constantine saw during the campaign against Maxentius, in which the Christian sign appeared in the sky with the legend “In this sign of victory”. Despite Caesar`s authority for reporting to Eusebius late in life, it is generally more problematic than the other, but a religious experience on the march of Gaul is also suggested by a pagan orator who, in a speech from 310, refers to a vision of Apollo received by Constantine in a sanctuary in Gaul. The word “tolerance” (Latin: tolerantia (“perseverance”) is often used to describe Rome`s position vis-à-vis the many indigenous cults. However, there was no official policy, and what was tolerated was religious pluralism; Everyone respected each other`s gods. Rome had a system of colleagues, merchants, and businessmen who gathered for meals together under the patronage of a god or goddess.