Isaiah prophesied around 740-701 BC.
For a child has been born to us, a son has been given to us.He shoulders responsibility and is called: Amazing Adviser, Mighty God, Everlasting Father, Prince of Peace.
At that time they will say, “Look, here is our God! We waited for him and he delivered us.Here is the Lord! We waited for him. Let’s rejoice and celebrate his deliverance!”
Micah prophesied between 735-715 BC
As for you, Bethlehem Ephrathah, seemingly insignificant among the clans of Judah – from you a king will emerge who will rule over Israel on my behalf, one whose origins are in the distant past
.."one of whose origins are in the distant past" can also be translated as "from days of eternity".
The Reformation Study Bible notes that Micah has learned that the ruler's origin long predates His anticipated future coming. A more-than-human figure is involved here.
Your throne, O God, will last for ever and ever; a scepter of justice will be the scepter of your kingdom. You love righteousness and hate wickedness; therefore God, your God, has set you above your companions by anointing you with the oil of joy.
This Psalm clearly identifies Christ as the divine King. We also catch a glimpse of the Trinity here when the Psalmist writes that God, your [Christ's] God will anoint Him. But Christ has already been identified as God!
Be sure to check out James White's book in the trinity called 'The Forgotten Trinity'.