For the entire history of Israel the Jews had been absolutely unwavering about their observance of the Sabbath. Suddenly, thousands of Jews abandoned this long-standing tradition in favor of worship on the first day of the week.

"On the first day of the week, when we were gathered together to break bread, Paul began talking to them, intending to leave the next day, and he prolonged his message until midnight." (Acts 20:7)

The writing of Justin Martyr, an early Christian leader of the second century, makes note of this same practice in the early church,

"And on the day called Sunday, all who live in cities or in the country gather together to one place, and the memoirs of the apostles or the writings of the prophets are read, as long as time permits." ¹