The 'Darkness' may simply represent evil, as it has for millennia. And the 'Light' represents that which is good. I don't see either as being a form of matter and/or being sentient in any way. I think the terms are simply storytelling. For example, the Light was swept away by the Darkness. Perhaps a reference to the Big Bang theory, in reverse, without having to say it. Yeah, I'm still working on that because it sounds ridiculous. Bare with me... In addition, there is at least one more thing in Destiny that, in my opinion, may have religious connotations without coming out and saying it. For instance, when our characters were resurrected by our Ghost. What, exactly, did it resurrect? We were dead for a long time, seemingly centuries. So, was it our spirit, our soul? That is, what made us, us. The essence of what made us individuals. At which point it was placed in the body we designed at the very start, before the scene in the Cosmodrome where our Ghost 'found us'. In other words we made a blueprint so to speak, from which our Ghost could create a body to place our spirit or soul in. Disclaimer: No psychotropic substance was involved in formulating this idea. >;)