"In those days a decree went out from Caesar Augustus that the whole empire should be registered. This first registration took place BEFORE Quirinius was governor of Syria" (Luke 2.1,2).

Augustus, also known as Octavian, ruled from 27 BC to 14 AD. He established a peaceful era (Pax Romana) and with that goes taxation and registrations.

The several censuses were conducted during his reign having this effect and summarizing the intention of these registrations. Evidence exists that Romans sometimes took registrations of client kingdoms. The Jewish historian Josephus wrote that Quirinius became governor of Syria and instituted a registration in in Judea in A.D. 6.

Jesus died 6 B.C.

Luke clearly knew of a subsequent registration: "After this man rose up Judas of Galilee in the days of the taxing, and drew away much people after him: he also perished; and all, even as many as obeyed him, were dispersed" (Acts 5.37).

"So everyone went to be registered in his own town" (Luke 2.3).

It is very unlikely this refers to the registration of Quirinius in AD 6, because this latter registration did not require Joseph to leave Galilee. It makes much more sense that this verse refers to Galilee and Judea ruled under one administration such as the reign of Herod the Great and not Herod's son Antipas. In 6 AD, Antipas ruled Galilee and a Roman prefect ruled Syria with control over Judea.