Final answer:
In Luke 2:1, Caesar Augustus issued the decree for the world to be registered, which is part of the nativity story.
Step-by-step explanation:
According to Luke 2:1, the decree that all the world should be registered was made by Caesar Augustus. This decree is an event in the biblical narrative where everyone was required to return to their own city to be registered. This is a significant part of the nativity story because it results in Joseph and Mary traveling to Bethlehem, leading to Jesus Christ's birth in that city in fulfillment of prophetic scriptures.