"Luther insisted on the Bible being the sole authority for all his teachings, but Eck challenged him on one point: sola Scriptura versus the authority of the Roman church and the pope.
Johann Eck, who was a staunch defender of Catholicism, challenged Karlstadt to a debate in Leipzig.
Then Luther entered the fray.
Eck stunned Luther with this challenge: “If, however the Church has had power to change the Sabbath of the commandment into Sunday and to command Sunday keeping, why should it not have this power concerning other [holy] days? If you . . . turn from the Church to the Scriptures alone, then you must keep the Sabbath [Saturday] with the Jews, which has been kept from the beginning of the world.”
Karlstadt must have been greatly impressed by this challenge, because from then on he strongly advocated the observance of the Sabbath on Saturday. His staunch support for the Sabbath caused Luther to write, “If Karlstadt were to write further about the Sabbath, Sunday would have to give way and the Sabbath—that is to say, Saturday—must be kept holy.”" SignsOfTheTimes
But the seventh day is the sabbath of the LORD thy God:
Johann Eck, who was a staunch defender of Catholicism, challenged Karlstadt to a debate in Leipzig.
Then Luther entered the fray.
Eck stunned Luther with this challenge: “If, however the Church has had power to change the Sabbath of the commandment into Sunday and to command Sunday keeping, why should it not have this power concerning other [holy] days? If you . . . turn from the Church to the Scriptures alone, then you must keep the Sabbath [Saturday] with the Jews, which has been kept from the beginning of the world.”
Karlstadt must have been greatly impressed by this challenge, because from then on he strongly advocated the observance of the Sabbath on Saturday. His staunch support for the Sabbath caused Luther to write, “If Karlstadt were to write further about the Sabbath, Sunday would have to give way and the Sabbath—that is to say, Saturday—must be kept holy.”" SignsOfTheTimes
But the seventh day is the sabbath of the LORD thy God:
Exodus 20:10