Exactly how did the Council of Nicaea in 325 and the Nicaean Creed change Christian's attitudes to Jews?

The subject of Judaism was not central to the Emperor Constantine’s decision to convene the Council of Nicaea in  325 AD, but the council’s actions certainly occurred against a backdrop of rampant anti-Semitism propagated by the Church. The most significant actions of those gathered in the city of Nicaea involved an agreement to recognize Jesus Christ as a divine being, as formalized in what became known as the Nicene Creed. The operative passage from the creed reads as follows:

We believe in one Lord, Jesus Christ,
the only Son of God,
eternally begotten of the Father,
God from God, Light from Light,
true God from true God,
begotten, not made,
of one Being with the Father.
Through him all things were made.

Constantine and others assembled placed the highest priority on a resolution of the debate over Jesus’s status because the Arians, followers of the priest Arius, rejected the notion of Jesus as a divine being on the same level as God. The Nicene Creed institutionalized among most Christians the status of Jesus as part of the “Blessed Trinity.”

With respect to the Council of Nicaea’s interest in the Jewish people, the council did adopt positions that further isolated the Jews by, among other acts, drawing a clearer distinction between the Jewish and Christian Sabbaths. This included manipulating the day on which Easter would be observed to ensure that it would be more distant from the Jewish observance of Passover. The council’s decisions came as close as possible without crossing a very delicate line in demonizing Jews by prohibiting marriages between Christians and Jews and by restricting business and other types of relationships. The Council of Nicaea is credited with laying the groundwork for subsequent councils to further institutionalize anti-Semitism within Christianity. Indeed, the Nicene Creed’s formalization of the notion of Jesus as a divine being, the result of internal Christian arguments over Jesus’s status, served to further isolate Jews by cementing the elevation of Jesus above figures revered by Jews, such as Moses.