Is the Seventh-day Adventist teaching that the Dark Ages spans from AD 538 to 1798 true?

Answer 1

Yes. But Seventh-day Adventists also believe the dark ages were cut short by the Protestant Reformation as predicted by Jesus. (See Matthew 24:21-22.) The span form 538 to 1798 is 1260 years, and corresponds to the 1260 days, 42 months, and "time, times, and half a time" of Daniel 7, and Revelation 12 and 13. This once was the interpretation of these prophecies held by nearly all protestant churches.