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.

Who alone comprehends the things of God?
What exhortation is based on the fact that God has forgiven us?
What assurance has the believer of his union with God?
To another whose sight He had restored, what did Christ say?
What view of the judgment scene was given Daniel?
How numerous are these wicked spirits, or fallen angels?
What is sometimes of greater value even than money to discouraged souls?

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