Matthew uses the reference to Christ as the Light (Isaiah 9:1–3) to give an implied reference to the rest of that prophecy (Isaiah 9:3–8), about Jesus as the promised Emmanuel (Matthew 1:22–23), the newborn King (Matthew 2:2, Matthew 2:11), and the Son of God (Matthew 3:17; Matthew 4:3,Matthew 4:6).
The light that will begin to shine in these areas, which were darkened early on, is the light of the Child born to us and who is known by the names Wonderful Counselor, Mighty God, Everlasting Father, Prince of Peace
(Isaiah 9:6). By reminding us of the very beginning of Isaiah’s prophecy (as recorded in Isaiah 8:22–9:3), Matthew draws our attention to that passage as a whole (Isaiah 8:22–9:8). Matthew had already earlier revealed to us that Jesus is the promised Immanuel (Matthew 1:22–23), the king who was born (Matthew 2:2, Matthew 2:11), and the Son of God (Matthew 3:17; Matthew 4:3, Matthew 4:6). Now that Emmanuel is going to establish himself in Galilee, the writer of the gospel highlights how this fits perfectly with what has been prophesied about him: the promised child will rise as a great light in the very area where Israel’s sun had long ago begun to set.1
14 so that what was spoken by the prophet Isaiah might be fulfilled: