Why did Constantine begin to support Christianity?

Answer 1

Saul is first mentioned in the Bible in Acts 7:58 at the stoning of Stephen. The religious leaders that stoned Stephen left their cloaks in Saul's care. Acts 8:1 states that Saul was approving of Stephen's murder. Following Stephen's death Saul went on a campaign of persecuting the Christians. Acts 8:3 says that Saul began invading one house after another and dragging both men and women from their homes and turning them over to the prison. Acts 9:1-2 states that Saul was breathing threat and murder against the disciples of the Lord and went to the high priest to get letters allowing him to bring bound to Jerusalem anyone who was a Christian
The doctrines of Christianity come mostly from the teaching or influence of Paul, a Pharisee(?) who rejected his Pharisaic Judaism. His worship was that of a "Christ" totally unrelated to the Jewish Messiah, a nationalist (and human) figure that was supposed to free the nation from foreign (Roman) rule. Paul would later be placed over his Jewish-Christian rivals by a Gnostic heretic named Marcion
According to a reasonable interpretation of the chronological evidence, Polycarp (while a bishop of Smyrna) was writing in AD 115 about the extensiveness of Marcion's teachings in Asia Minor (Pol. Phil. 2:18,19). Polycarp styled Marcion as "the first-born of Satan" (Ante-Nicene Fathers [ANF] vol. 1, p. 416), and the object of Polycarp's criticism in his Epistle to Philippi is directed to this same "[son]."
About the year AD 138, Justin Martyr (a resident of Rome) wrote about Marcion's unusually long and effective teaching career. "And there is Marcion, a man of Pontus, who is even at this day alive, and teaching his disciples to believe in some other god greater than the Creator. And he, by the aid of devils, has caused many of every nation to speak blasphemies, and to deny that God is the maker of this universe, and to assert that some other being, greater than He, has done greater works. All who take these opinions from these men are, as we before said, called Christian" (Justin's [First] Apology. I.26. ANF. vol. 1. p. 171). The reason for dating this statement to the year AD 138 is discoverable in Blackman's study (Marcion and His Influence. p. 21).
One of the most startling things in Justin's unfavorable review of Marcion is the surprising appearance of the word "Christians" as a commonly used title to describe the members of Marcionite churches. By AD 138, Marcionites could be found in "every nation." At this early time, there is some confusion about the correct spelling for "Christian." It is known that Marcion preferred to call Jesus the "Chrestos" (which means the Kind or Helpful One). "... [T]he spelling for 'Chrestos' (=the Good one) [is] derived from an ancient inscription to a Marcionite synagogue" (Daniel Jon Mahar. English Reconstruction and Translation of Marcion's version of To The Galatians. p. 1).
Not many know that the Sinaiticus manuscript has a peculiar way of spelling the word Christian. Everywhere this title appears, that Fourth Century manuscript spells it "Chrestian." Vaticanus, a manuscript of the same age, utilizes a slightly transitional spelling: "Chreistian."
In AD 49, Rome experienced disturbances in the Jewish community that had been provoked by the preaching of "Chrestus" (based on the account of Suetonius in J. Steven's New Eusebius. no. 2, p. 1). "[Aquila] and his wife Priscilla had recently left Italy because an edict of Claudius had expelled all the Jews from Rome" (Acts 18:2, Jerusalem Bible). It seems notable at this time (AD 49) that "Jews" in general were expelled, and not simply followers of "Chrestus" or "Chrestians." "Was it because at this early date the Roman authorities did not or could not clearly differentiate between the Christians and the Jews?" (Wilson. Marcion... p. 25). The presence of the Gentile title "Chrestus" in Rome implies also the presence of an accompanying Gentile-oriented Gospel. Some Jews seem to have loudly voiced a degree of intolerance upon hearing this proclamation of "Chrestus."
The two titles "Chrestus" or "Chrestian" are referred to in the following written sources: Tertullian (AD 210), The Eighth Sibyl (AD 200), Theophilos of Antioch (AD 170), Marcus (AD 145), Apocalypse of Elijah (AD 100), Suetonius (AD 124) and Tacitus (AD 116). There is even a disputed inscription (now lost) from Pompei (AD 79) that is believed to have contained a reference to this lost title of Jesus.
Prior to Marcion's revival of Paul's theology, Christianity was much identified with Judaism. At that time, the Christian Bible was only the Old Testament. After Marcion openly published the first New Testament in Rome (AD 116), there arose four great divisions in Christianity. These groups were denominated: the Gnostics, the Catholics, the Judeo-Christians and the Marcionites.
Before Marcion published the first truly Christian Bible, Christianity already had been divided into two groups. In Paul's words, there were the "Judaizers" and there were the Pneumatics (the "Spiritual"). The Judaizers were more allied with Peter and James. The Pneumatics upheld Paul's Gospel of freedom.