Do Protestant writers acknowledge the same?

Answer

They do.
NOTE - "IS there no express commandment for observing the first day of the week as Sabbath,
instead of the seventh day?-None whatever. Neither Christ, nor His apostles, nor the first Christians
celebrated the first day of the week instead of the seventh as the Sabbath."-New York Weekly Tribune,
May 24, 1900.
"The Scriptures nowhere call the first day of the week the Sabbath. . . . There is no Scriptural
authority for so doing, nor of course any Scriptural obligation." The Watchman (Baptist).
"The observance of the first instead of the seventh day rests on the testimony of the church, and
the church alone.' -- Hobart Church News, July 2, 1894.
For additional testimonies, see reading on page 146.

When was Jesus born?
What did Jesus present to the people as a basis of confidence in Him?
How early were the Scriptures taught to Timothy?
What is said of the fourth kingdom?
How are the people described who are developed by the threefold message here referred to?
How do evil spirits sometimes treat those thus possessed ?
Is there danger of believers losing their hold on Christ?

Questions & Answers are from the book Bible Readings for the Home Circle