I love that verse found in Isaiah 60:1. I use it all year round, but at this time of year it reminds us that God is faithful and always fulfills His promises.
Isn't it interesting that God wrote this in the past tense? To Isaiah, it was as if the Light had already come when it would be centuries before Christ would be born. I love it when God talks in the past tense because it makes it so done-dealish. It's a fact, Jack. No questions, Sessions. Isaiah already had his Messiah, the time/space continuum just hadn't caught up with God, yet.
So, I hold on to this verse all year, because it is an assurance to me that God is who He says He is, and God has done what He said He would do. Since God is so very consistent and constant, this is the assurance that all the rest of prophecy will come about just as it was foretold and is written.