[antisocial]

"oh my - tradition, as determined by the Catholic bishops long after the deaths of Jesus and the early apostles."

As determined by the emperor Constantine and his mother! they refused to allow any worship on the Sabbath because the evvvil JUES worshiped on the seventh day. They also incorporated many of the local pagan customs like winter solistice,Easter(fertility rites)into their version of Christianity. Look in the encyclopedia Britanica under Christmas and see what it says about its origins.
Jesus was a devout Jew and observed the Holy Days (Seven Festivals of the Lord) as the Old Testament required.

[familyop]

"As determined by the emperor Constantine and his mother!"

Yes. Also, in 321, the Emperor Constantine (while he was yet worshipping the sun) decreed Sunday to be the day of rest. Constantine said, "On the venerable day of the Sun let the magistrates and people residing in cities rest, and let all workshops be closed."

The Church Council of Laodicea ordered Sunday to be kept by Christians as their sabbath in 364. During the 100s of years after that, the Inquisition was sometimes used to enforce it.