Most. So, their are two days the Sabbath (Saturday, 7th day of week) and the Lord's Day (Sunday, 1st day of week). The Catholic Church changed to the Lord's Day[1]. Some Christian Churches don't recognize the authority of the Catholic Church to change the day of worship. Two examples would be Seventh Day Baptists and Seventh-day Adventists.

1) reasons http://www.vatican.va/archive/ccc_css/archive/catechism/p3s2...