World War 3 is at Hand
God prepared Saul a Pharisee of Pharisees to be the apostle of the Gentiles to protect the Gentiles from being coerced into the heretic Judaizers.
Similarly, before God hands over the Roman Empire and the rest of the world to Christianity, He ensures that His truth and the genuine inspired gospels and apostles' epistles were available to all bishops and Christians.
Vision of the Cross
Constantine was heavily outnumbered and he was advised to withdraw but there was no doubt in his mind that he would be victorious for on the eve of the battle he'd had a vision. The historian Eusebius described what happened: "He saw with his own eyes in the heavens the Cross arising from the light of the sun, carrying the message _In Hoc Signo Vincesa_ - In This Sign Conquer.
On October 28 in 312 A.D. Constantine defeated the superior forces of his rival Maxentius at the battle of Milvian Bridge. Immediately, he attributed the victory to the God of the Christians.
the Cross arising from the light of the sun
Mat 5:16 "Let your light so shine before men, that they may see your good works and glorify your Father in heaven."
Constantine, having the understanding of the light and love of Christ at the Cross, was commissioned by God to evangelize the whole Roman Empire.
With great humility he made peace with Emperor Licinius of the Eastern Roman Empire and later with the love and patience of Christ he convinced the powerful Pagan Senate to legalise the Christian religion. So in February 313 AD the Roman emperors Constantine (Western Roman Empire) and Licinius (Eastern Roman Empire), signed the edict of Milan proclaiming religious toleration in the Roman Empire and removed the persecution of Christians.
Mission of Constantine
The Church generally regarded the definition of doctrine as the responsibility of the bishops; the emperor's role was to enforce doctrine, root out heresy, and uphold ecclesiastical unity.
The Nicene Creed
In 325 he summoned the First Council of Nicaea, effectively the first Ecumenical Council (unless the Council of Jerusalem is so classified). The Council of Nicaea is the first major attempt by Christians to define orthodoxy for the whole Church.
Constantine brought together 1,800 faithful, godly and persecuted bishops from around the empire to work out the official doctrine and provide the basis for a unified Church.
The bishops with the guidance of the Holy Spirit produced the Nicene creed, which summarizes the apostles' preachings and teachings concerning the triune Godhead (Trinity) and the gospel of Jesus Christ. This creed protects the church from early heresies and deviations from orthodox Christian doctrine.
Note. From the Apostles' Creed:-
1. Arianism, which rejects the triune Godhead, and
2. Judaizers, which adds the works of the Law to the Grace of Jesus, are heretic.
Canon Books of the Bible
At that time, there were about 50 Gospels (Gospels of Thomas, Marcion, Mary Magdalene, Barnabas, etc.) and many Epistles which claimed to be holy scriptures. The Council of Laodicea (AD 363) was tasked to canonise this large amount of writings.
The principles used by the councils to determine whether a New Testament book was truly inspired by the Holy Spirit were fourfold.
First, the author must be an apostle or have a close connection with an apostle.
Second, the book must have been accepted by the body of Christ at large.
Third, the book had to contain consistency of doctrine and orthodox teaching.
Finally, the book had to bear evidence of high moral and spiritual values that would reflect the work of the Holy Spirit as the divine Author.
The Council of Laodicea concluded that only the Old Testament (along with the Apocrypha) and the twenty-seven books of the New Testament were to be read in the churches.
With the Apostles Creed, the canon books of the Bible and the empowerment of the Holy Spirit of truth, Christians are well equipped to the knowledge of the truth in His word.