Wow, that's quite a question.

I'm guessing you realise providing a full answer to this question is impossible. Greater men have tried and failed.

Our perceptions and empirical sciences states there is no proof either way. Psychological theory states that God comes hand in hand with Consciousness, some sort of defense mechanism of a primitive mind trying to make sense of it all, to provide Meaning. Brain scans have shown a particular region of the brain that "awakens" when people have spiritual experiences, nicknamed the "God Spot", almost as if God created us with a biological facility for belief.

And on the other hand, we have religion and faith, practiced by about 99 percent of the world's population, in some way or another. It is kind of hard to argue that such a large portion of the world is suffering from some sort of delusion. 

And God itself, how do you define God? Are you speaking of an all powerful being that created our world and continues to govern it? Or just an intelligent set of governing rules that apply to the universe, a higher force? 

My opinion? I do not think humanity needs a God figure in order to be spiritual. This is the last step before fully realising we are nothing more than a mass of smart molecules, but that doesn't mean we aren't spiritual. Transcedence is possible without an God figure.

This shouldn't stop at a mere question/answer. This should continue into a debate.