This is what happened. In the early fourth century, Roman emperor Constantine tried to use the “Christian” religion of his day to cement his disintegrating empire. To this end, he granted professed Christians religious freedom and transferred some of the privileges of the pagan priesthood to their clergy class. The New Encyclopædia Britannica states: “Constantine brought the church out of its withdrawal from the world to accept social responsibility and helped pagan society to be won for the church.”

The turning point came early in the fourth century with the so-called conversion to Christianity of Emperor Constantine I. Concerning this “conversion,” the French work Théo​—Nouvelle encyclopédie catholique (Théo—​New Catholic Encyclopedia) states: “Constantine claimed to be a Christian emperor. In reality, he was baptized only on his deathbed.” Nevertheless, in 313 C.E., Constantine and his coemperor, Licinius, issued an edict that granted religious freedom to Christians and pagans alike. The New Catholic Encyclopedia states: “Constantine’s extension of freedom of worship to Christians, which signified that Christianity was recognized officially as a religio licita [lawful religion] beside paganism, was a revolutionary act.”

However, The New Encyclopædia Britannica declares: “He [Constantine] did not make Christianity the religion of the empire.” French historian Jean-Rémy Palanque, member of the Institute of France, writes: “The Roman State . . . remained, however, officially pagan. And Constantine, when adhering to the religion of Christ, did not put an end to that situation.” In the work The Legacy of Rome, Professor Ernest Barker stated: “[Constantine’s victory] did not result in the immediate establishment of Christianity as the religion of the State. Constantine was content to recognize Christianity as one of the public worships of the empire. For the next seventy years the old pagan rites were officially performed in Rome.”

So at this point “Christianity” was a legal religion in the Roman Empire.