There was a good thread on the message boards about this not too long ago. I can’t locate it, since the search engine for the Message Board is still kaput, but basically, the SDA reason for celebrating the Sabbath on the same day as the Jewish Sabbath has to do with passages in the Bible that make it clear (to them) that Jesus rose on the day AFTER the Jewish Sabbath. I recommend reading the thread in question; it did a good job of explaining the argument.
Huh? Of course Jesus rose on the day (Sunday) after the Jewish Sabbath (Saturday). That was never an issue at all. The overwhelming majority of Xtians have always celebrated Sunday for that reason. Just when Sunday became “the Christian Sabbath”, on the other hand, is a bit fuzzier. (Indeed, it only reached full fruition in modern times, with the Puritans.)
John W. Kennedy
“Compact is becoming contract; man only earns and pays.”
– Charles Williams