This “holistic” mode of consciousness (which Luthor experiences briefly at the end of All Star Superman) announces itself as a heartbreaking connection, a oneness, with everything that exists…but you don’t have to be Superman to know what that feeling is like. There are a ton of meditation techniques which can take you to this place. I don’t see it as anything supernatural or religious, in fact, I think it’s nothing more than a developmental level of human consciousness, like the ability to see perspective – which children of 4 cannot do but children of 6 can.
Everyone who’s familiar with this upgrade will tell you the same thing: it feels as if “alien” or “angelic” voices – far more intelligent, coherent and kindly than the voices you normally hear in your head – are explaining the structure of time and space and your place in it.
This identification with a timeless supermind containing and resolving within itself all possible thoughts and contradictions, is what many people, unsurprisingly, mistake for an encounter with “God.” However, given that this totality must logically include and resolve all possible thoughts and concepts, it can also be interpreted as an actual encounter with God, so I’m not here to give anyone a hard time over interpretation.