 Constantine enforced the prohibition of the First Council of Nicaea against celebrating the Lord 's Supper on the day before the Jewish Passover ( 14 Nisan ) ( see <unk> and Easter controversy ) . This marked a definite break of Christianity from the Judaic tradition . From then on the Roman Julian Calendar , a solar calendar , was given precedence over the lunisolar Hebrew Calendar among the Christian churches of the Roman Empire . 
