So heres the story…
This song is based on Chassidus/Kabbalah specifically from the book of Tanya (by Rabbi Shneur Zalman of Liadi, the founder of Chabad Hasidism)
I’l try and sum it up… here goes:
The soul before it comes down into the body (born) is basking in the glory and light of G-d in heaven. Then it is told it must come down into this world of darkness. Why does the soul have to leave the light? It’s mission is to elevate this low world, to turn the darkness here into light. We are all warriors because we have to struggle with the darkness. We also have to struggle with our selfish side. The side that wants us to forget why we are here and just enjoy itself.
G-d is the “King”. We are the “prince” and the “priest”. We all come from a very high place. Matisyahu is singing to the soul - “remember who you used to be”, stay focused.
Then “One Day” after we make all the darkness shine. After we elevate this world to a pure and holy place, G-d will feel welcome and He will reveal himself - the Prince will be reunited with the King. May it happen now. (We want Moshiach now!)
Listen to the song now and you will hear it all. However like some above have said above - lyrics in general are loose and everyone takes it personally and gives it their own meaning.
I hope I didn’t “spoil” it for anyone - I just happened to have studied the Tanya and knew what he was referring to.
All the best!