Final answer:
''For unto us a child is born'' is from the biblical account of the nativity of Christ and represents the moment of Jesus' birth and the joyous news of the coming of the Messiah.
Step-by-step explanation:
The phrase ''for unto us a child is born'' is from the biblical account of the nativity of Christ. It is specifically from the book of Isaiah in the Old Testament, which is an important text in Christianity. The phrase is often associated with Christmas and the birth of Jesus. In the context of the nativity scene, it represents the moment of Jesus' birth and the joyous news of the coming of the Messiah.