To whom does Micah 5:2 refer and how should we understand the phrase, “whose goings forth have been from of old, from everlasting”?

This is a prophecy about Jesus, the Messiah. It probably had a preliminary fulfillment in the times of Micah, but it’s ultimate fulfillment is in Jesus. The prophecy is about someone who will rescue Israel from the Assyrians.

Old Testament prophecies sometimes have multiple fulfillments. We see that especially in the prophecy from Isaiah we talk about during Christmas about the virgin giving birth in Isaiah 7. That one is also a messianic prophecy about Jesus. It is fulfilled in the beginning of the Gospels.

In the same way, we can understand this prophecy to be partially fulfilled in the times that it was given, but its ultimate fulfillment is in Jesus. It is even quoted by the scholars King Herod consults when he asks about the special birth of this king (Matthew 2:5-6).

This is very significant because it means that even the scholars in the day that Jesus was born consider this a prophecy about a Messiah who had yet to come upon the scene. So it had a minor fulfillment in its time but looked forward to the ultimate fulfillment of the Messiah, Jesus.

It’s confirmed even more in the quotation you mentioned in your question. Micah prophesies that Bethlehem will be the place that the Messiah will come out of. Little did they know in the day of Jesus that he was not born in Nazareth, but Bethlehem.

Calling Jesus the ruler of Israel looks forward to his second coming when he reigns on the throne of David for a millennium from Israel. The next phrase refers to the divinity of the Messiah Jesus. Speaking of his “coming forth from of old, from ancient days” speaks of his eternal nature.

Jesus is divine and the prophets of the Old Testament pointed out when they talked about the Messiah. The phrases they use refer to divinity and eternity. Jesus fulfills all of this because he is the Son of God who came from heaven to earth.