The Catholic Church claims that Jesus Christ was born on December 25, 1 BCE. However, it is greatly mistaken. The true date of Jesus' birth is Nisan 1, 5 BCE, which, if calculated correctly, corresponds to March 9/10 in the Julian calendar. He was conceived on Sivan 3, 6 BCE, which, if calculated correctly, corresponds to May 19/20 in the Julian calendar.
Jesus was conceived on the very day that the power of God covered Mount Sinai and gave Moses the law: Sivan 3 (Exodus 19:1, 16; Luke 1:35). For just as Mount Sinai was covered by the power of God, so Mary was covered by the power of God, and just as Moses received the Law, so Mary received the Son of God in her womb. And exactly 42 weeks later, Jesus was born on the very same day that God's tent was completed: Nisan 1 (Exodus 40:2, 34; John 1:14). For just as God's tent was completed, so too was the body of Jesus completed to be born.
It makes no sense that Jesus was born on December 25 because this date has no connection to the Old Testament. Jesus was certainly born on a significant day of the Old Testament. 1 BCE as his birth year also makes no sense because Herod died in 4 BCE. Jesus must have been born before 4 BCE. Catholics should wake up from their error and repent.
Constantine was born on February 27, 272 CE. That law from Constantine officially declared a day of rest on Sunday. What day do many Christian groups consider the Sabbath? Sunday. What day is it in the OT? Saturday. Whether Constantine or your buds before 40 CE, seems kind of erroneous to think of Sunday as some kind of Christian Sabbath.
When was Jesus born?
Again you're wrong, because you forge ahead with nothing but your own assumptions.
Sabbath is irrelevant.