The Roman Catholic Church Admits It
The Catholic Church's own words about changing the Sabbath
These are not accusations from Protestants. These are official Catholic statements, published by Catholic authorities, in Catholic publications.
"The Catholic Church...by virtue of her divine mission, changed the day from Saturday to Sunday."
The Catholic Mirror (Baltimore), September 1893
"You may read the Bible from Genesis to Revelation, and you will not find a single line authorizing the sanctification of Sunday. The Scriptures enforce the religious observance of Saturday, a day which we never sanctify."
James Cardinal Gibbons, The Faith of Our Fathers (1876)
"Of course the Catholic Church claims that the change was her act...And the act is a mark of her ecclesiastical power."
H.F. Thomas, Chancellor of Cardinal Gibbons
"The observance of Sunday by the Protestants is an homage they pay, in spite of themselves, to the authority of the Catholic Church."
Monsignor Louis Segur, Plain Talk About the Protestantism of Today (1868)
"Protestants...accept Sunday rather than Saturday as the day for public worship after the Catholic Church made the change...In observing Sunday, they are accepting the authority of the spokesman for the Church, the pope."
Our Sunday Visitor (Catholic weekly), February 5, 1950
The Same Pattern: The Creed
The Sabbath change was not the only unilateral alteration. In 1014 AD, Rome inserted the word filioque (“and the Son”) into the Nicene Creed, changing “the Holy Spirit, who proceedeth from the Father” to “who proceedeth from the Father and the Son.” No ecumenical council authorized it. The Eastern Orthodox churches rejected it. The filioque was the primary theological cause of the Great Schism in 1054 AD.
These two changes follow the same pattern. Both were made by Rome alone, neither was authorized by an ecumenical council, and both were rejected by the Eastern churches.
The Question
The Roman Catholic Church admits they changed the Sabbath from Saturday to Sunday.
The Roman Catholic Church admits there is no biblical authority for Sunday worship.
The Roman Catholic Church admits Protestants who keep Sunday are following Catholic authority, not Scripture.
Every Sunday-keeper must decide whose authority governs their worship.