Constantine I

Constantine I was the first Christian Roman emperor, and he also helped evolve the empire into a Christian state during the fourth century. Under his rule, Jewish people were forbidden to own Christian slaves and to circumcise slaves. He ordered the confiscation of the property of Christians who embraced Judaism, and he issued a law that forbade marriages between Jews and Christians, which was punishable for Jewish people with the death penalty. Constantine also prohibited Jews from proselytizing and from visiting and settling in Jerusalem. All Roman emperors after Constantine, except Julian, were Christians.

Council of Nicaea
The Council of Nicaea was convened by Constantine in 325 and mandated the separation of the celebration of Easter from the Jewish calendar. Constantine on the results of the Council of Nicaea: “... It was declared to be particularly unworthy for this, the holiest of all festivals, to follow the custom of the Jews, who had soiled their hands with the most fearful of crimes, and whose minds were blinded. ... We ought not ... to have anything in common with the Jews, for the Savior [Jesus Christ] has shown us another way; our worship follows a more legitimate and more convenient course; and consequently, in unanimously adopting this mode, we desire, dearest brethren, to separate ourselves from the detestable company of the Jews, for it is truly shameful for us to hear them boast that without their direction we could not keep this feast. How can they be in the right, they who, after the death of the Savior, have no longer been led by reason but by wild violence, as their delusion may urge them? They do not possess the truth in this Easter question; for, in their blindness and repugnance to all improvements, they frequently celebrate two passovers in the same year. We could not imitate those who are openly in error. How, then, could we follow these Jews, who are most certainly blinded by error? for to celebrate the passover twice in one year is totally inadmissible. But even if this were not so, it would still be your duty not to tarnish your soul by communications with such wicked people [the Jews]. ...”