Different sects dispute over what is the central day of the week for religious purposes.
There is the Sabbath and there is the Lord’s Day. Rome has been accused of changing the Sabbath from Saturday to Sunday for its members.
The first and most important day is always Shabbat, which is, has always been, and will always be, from sundown on Friday to sundown on Saturday.
But, the Lord’s Day (Sunday) is also very important.
This is how we view it:
Saturday is for the study of Tanakh.
Sunday is for the study of Gospels and the religious text of the apostles etc.
One does not need to replace the other. One is a day of rest, the other is a day of celebration.
You don’t have to choose.
If someone tries to tell you that Saturday is no longer the Sabbath, don’t believe them.
If someone tells you not to gather on Sunday to celebrate the risen Mshikha, don’t believe them.
Two separate days that serve two very different and two very important purposes.