That's one thing you got right. No need to worry about anything Jewish being left in.
From the Council of Nicea (325):(excerpted)
It was declared to be particularly unworthy for this, the holiest of all festivals, to follow the custom [the calculation] of the Jews, who had soiled their hands with the most fearful of crimes, and whose minds were blinded.In rejecting their custom,(1) we may transmit to our descendants the legitimate mode of celebrating Easter, which we have observed from the time of the Saviour's Passion to the present day[according to the day of the week]. We ought not, therefore, to have anything in common with the Jews, for the Saviour has shown us another way; our worship follows a more legitimate and more convenient course (the order of the days of the week); 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 Saviour, 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].
That's why the church needed to change the calendar, needed to do away with the Sabbath and started Sun-day worship, in 'honor of the venerable Sun'. Why they needed to distance themselves from Passover and celebrate Easter, a name derived from the pagan godess of fertility, widely known at the time.
The church has done nearly all it could to distance themselves from the root that they 'claim' to be grafted unto. Yet, it resembles nothing of the root anymore.
The part I want to specifically point out is this: for the Saviour has shown us another way;
An actual admission that the church has deviated from 'the way' and gone after 'another way'!! And to top it off, they give credit to Yehoshua for this 'new way'. The church admits that this 'other way' is more CONVENIENT!
That's one thing you got right.
Then what is your argument?