This song is about an emotion journey someone is going through.
It starts by describing from the 3rd person that they are unhappy, depressed, and feel like there’s no more hope.
Then, an angel (or spiritual figure) comes in and says “I’ll guide the way”. The angel will show this person that there are so many reasons to be joyful.
The first chorus explains that if you only focus on the negative, that is exactly what comes your way.
However, if you manage to see that there is light and love within you, you will begin to see it around you as well.
The second verse is all about the beauty of Christmas. It is a metaphor for what emotions we experience as humans, as Christmas is associated with positive ones.
The second chorus engrains the idea that love has to come within you, and you can’t just wait for something external to influence how you feel. Once you start loving yourself, you will love other people and things too.
I’m not religious, and I always felt uncomfortable with the concept of only doing good things because someone is “watching over us”. I think we should be kind to each other regardless of the consequence. Hence, the last line, which is a bit of a hint towards Christmas “it comes from within, and not from above”.