Well this theme song can be a subject to change in the society if only you understand the meaning of the lyrics but am just going to give it a literal explanation. Then you make your own interpretation based on what you've understood in the Boondocks series.
I am the stone that builder refused:(This talks about complete ignorance. Stone, cement and water are very essential to a builder and stone especially is needed for laying foundations so when you are trying to build a structure and you choose to ignore one essential component, your foundation is weak and your building will definitely crumble in the nearest future).
I am the visual.
The inspiration.
That made lady sing the blues:(Vision is a gift from the Almighty. Vision and Inspiration are used as synonymous terms here, where vision is the physical sight, inspiration is the inner sight. So penetrating ones inner sight is also a gift. The refused stone has assumed the position of a man here by the qualities he has placed on himself. Men are known to be the sight and women are the mind. Therefore making ladies sing the blues has to do with a deeper understanding between the refused stone and his soul mate{note: blues are songs much loved and appreciated by women which creates a form of intimacy unlike rap and hip-hop which are more appreciate by men folks})
Am the spark that makes your idea bright:(Ideas are products of thinking, if you are given wrong informations, your thinking would most def be in the wrong way and if you are given the right infos, ur thinking would be in the right way. That same refused stone is a spark or light which gives you right infos and makes you think in the right direction therefore making your ideas bright).
The same spark.
That lights the dark.
So that you can know your left from your right:(When you are caught up in a dark place, even with your eyes wide open, you are completely blind and do not know where to go, if it wasn't very dark you can as well as create a light for yourself but in a case of total darkness, you could get lost, you can be killed, manipulated, or you could choose to keep still until you find a light which would guide your movement. Well the same refused stone won't give you a complete light to guide your movement but just a spark so that you can know your left from your right;)
I am the ballot in your box.
The bullet in your gun (A ballot box is useless without ballots in it, a gun is also useless without bullets in it. So still back to the first point, emphasis have been placed on that refused stone just for you to capture it's inevitable importance).
The inner glow that lets you know.
To call your brother son (Its kind of an irony calling your brother son tho, but when conditions becomes critical and you know you are in a better state of taking responsibility than a so called father, you replace the role of your so called father and your brothers and sisters bcoms sons and daughters to you)
The story that just begun.
The promise of what's to come (In a Prophetic view of reasoning, promises are meant to come to pass, so when you are more of a spiritual being, you'll believe in prophesies yea! So the refused stone whose story has just begun is going to fulfil a Prophesy which will come to pass later on).
And I'm 'a remain a soldier till the war is won (The duty of a soldier is to fight for a specific course, so the refused stone has chosen the role of a soldier to defend his territory and fight for what's truly he's until he assumed the position he plays in the building of his foundation).
Now the question you should be asking is who is this refused stone? Well watch the Boondocks and find out. Even an average minded person can figure that out real quick.
Peace.
Mastermind.