By what authority was Sunday Sabbath-keeping instituted?

Answer

By the authority of the Catholic Church. See page 131.

3. By what comparison is it indicated that some portions of God's Word are more difficult to understand than others?
By whom were the heaven and the earth created?
How may we determine the truthfulness of any doctrine ?
After He had prayed this remarkable prayer three times, what occurred?
22. What did Augustine, the father of this theocratical or church-and-state theory, teach concerning it?
What directions were given by Constantine's Sunday law of March 7, 321?
How will the righteous ever afterward appear?

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