Constantine, one of the men that brought the church of Jesus Christ into pagan worship and forbade them from keeping the Sabbath (God’s commandments & holy seasons).

Article; By Rick Aharon Chaimberlin

The Council of Nicea was convened in the year 325 CE (AD) by Constantine, Emperor of the Roman Empire.

Constantine the worshipper of the ‘sun-god,’ technically ‘converted’ to Christianity.
His reign marked the alliance or the combining of strength of church (catholic church) and state. 

Constantine kills and sacrifices to gain power.

Constantine, only one year after convening the Council of Nicea, had his own son (Crispus) put to death.

A statue of Constantine 
Later he suffocated Fausta (his wife) in an overheated bath. Then he had his sister’s son flogged to death and her husband strangled.

When did the cross become a symbol of the Catholic church?

It was also during the reign of Constantine that the cross became a sacred symbol in Christianity, just as it had been in pagan religions. On the cross Jesus is depicted to be defeated by Tamuz the pagan god cross, that is why his image is still hanging on the cross, as a symbolic sign that he has never risen, because he is still defeated and bound by the cross, the cross being Tamuz.

These events of paganizing the Christian church took place in the year 325 Ce

The council of Nicea was also the one that established the teachings of Nicolaitans by including them in their constituted laws that will govern the Christian church.

And everything pertaining to the Hebrew God, (God’s seasons, Holy feasts, God’s calendar etc) which pointed at the Hebrew Jewish Messiah or Yeshua, were all taken away from the Christian Holy days, and replaced by the pagan feast of Easter, Saturnalia, Sun day etc.