I imagine God (if exists) to be an omnipotent and omnipresent sentient driving force of the Multiverse. A force that created (and creates?) all the Universes with their rules and, thus, his existance is "spilled out" everywhere. If that is true, then keep in mind that this force doesn't "care" for us. At least the way we mean it perhaps.
I have no well thought theories about an afterlife though.
Don't forget that we 've been tought from Physics that action and reaction exists. So what we would call "God" is an action without previous reaction. The action that started all. (....Wow
)




?.