No, the only requirement it wield the Light is faith in its power. Right or wrong is not required, just a belief that the power will aide you. You can use it without worship, as long as you believe in your ability to be empowered by it. Shadow is very similar, though faith is the wrong word. More desire. A desire for shadow’s power and receptiveness to the darkness it brings.
Pretty much:
Light is a faith based power. Not religious faith, but a faith in its ability and ones’ own ability. You do not need to worship it or some other religion to use it, just believe that you can use it. “I CAN use the power of the Light!” To much Light is a bad thing, blind faith in it is a bad thing.
Shadow is a desire based power. No belief in any system, just a want to use it. No religion required. It is, depending on who you ask, more dangerous than the Light. “I WANT to wield the power of Shadow.” To much Shadow is a bad thing, wonton desire for it is a bad thing.