I think as human ability for rational thought has evolved, so too has anxiety about things we don't know. To survive, our ancestors needed to know and understand from where and how to get their food, shelter, mates, etc...  They needed to understand how the future might play out and then plan for this. So along with the ability to understand  the world and make plans comes anxiety about things we don't know.

So, God, gods, myths, legends and religion have served as an explanation about things we don't know. This relieves the anxiety about the unknown, so religion has served as an anti-anxiety drug. We see this today, God is the explanation for everything science has yet to explain. So while many religious people are accepting Darwin's explanation for the origin of species, they still use God to explain the origin of life and the universe. God is just relief for the anxiety about things we don't know.

So I think religion will die out when science comes up with a better anti-anxiety drug than religion.

You could be right that if we don't destroy ourselves and religion is greatly diminished, perhaps this universal conscience could arise. Who knows? Another mystery of the universe.

There are as many reasons the concept of god exists as there are gods - and human history has thrown up quite a range and variety.

But one reason, to me, overrides the rest, underpins most religious pseudo-philosophy, and it is to do with betrayal and the limitations it suggests. We are, and our ancestors were probably even more so, obliged to place our trust in certain things. We simply cannot function if we do not do so. I am not talking about the usual "big" items of faith such as the sun coming up again the next day, or gravity working, or the seasons running in the right sequence etc. These have undoubtedly been items of blind faith for countless millennia also (since few or none understood the mechanism nvolved), but to put it bluntly, if any should - for some weird astronomical reason - cease to occur no one would be around to realise their misplaced trust, or at least not for very long.

Instead however I'm thinking of the little, but crucial things. We trust that we can cross the road without getting killed by oncoming traffic. We trust that we can go outside our doors without getting mugged. We trust that we can remember crucial information just when it's required. We trust that we will have the wherewithal to eat the next day.

And here is where god comes in, or at least the beginning of the desire to believe in one. Unlike with the big assumptions of faith, these "little" ones are being consistently challenged by fact. All of us have had near misses (or worse) when crossing roads. All of us have had direct or indirect experience of a mugging or other form of unprovoked aggession against us. All of us have screwed up to some degree due to fawlty or non-existent memory of something crucial when it was required. All of us (or at least a lot of us) have had the experience of going hungry when we expected to eat.

Countless other situations and scenarios can be added to this list since they represent ordinary day-to-day life as it is for the bulk of us, and has been for the bulk of humanity since human consciousness emerged. What they have in common is betrayal of trust, again and again, but in situations where we as humans are obliged to ignore the setback and continue placing trust in that which betrayed us - the alternative being to lessen our potential to survive. This represents a huge dichotomy between the way our brains are hard-wired to respond to adverse situations and reality itself. We are geared to learn from our mistakes and are so well conditioned in that respect that we will equally learn from the mistakes of others (essentially what education could be said to be all about). We are programmed to identify, and thereby hopefully eliminate dangers as they arise or based on information transmitted to us by our fellow humans.

These countless little betrayals, some of which are often fatal, fly in the face of that programming.  Sometimes they even call into question whole and entire principles or facts which we all have assumed to be unquestionably predictable in their behaviour. Yet to admit to that unpredictability goes against the grain so much that they must be at least accounted for if not explained to the point of prediction. They must be compartmentalised, if only to free the brain up to move on to the next problem it has to solve in its owner's battle to stay alive. The alternative is a feeling of insecurity, and we all know what that can do to our ability to make value judgments.

Roll up god (or allah, or jehovah, or buddha, or zeus & co, or mithridates or whoever you want). He doesn't have all the answers - in fact gods tend to ask more questions of people than they answer, at least with any useful information. But he provides a sketchy but workable "filler" for the gap created by misfortune and unpredictable events. The gap is not a knowledge gap, which is why fundamentalist christians cannot appear as anything but stupid to anyone with at least two working brain cells. Nor is it a happiness gap, since religion for all its claims cannot guarantee any respite from sadness - merely a balm based on promises the evidence for which can never be presented in reality. The gap is a "trustworthiness" gap which allows the subscriber to "move on" quickly after a setback, or even to face the certainty that such setbacks will occur, without losing faith in their own abilities. It is, in other words, a survival tool - and in the past was probably one of the most important survival tools there was.

But that was in the past. Education, and in particular scientific analysis of the situations hitherto deemed to be always unpredictable (or at least un-understandable) has not only begun to eliminate, but has gone a good way towards eliminating those doubts. But it has happened quickly, way too quickly for humanity as a race to accept that the hard-wiring warrants an overhaul. In fact such a race-wide overhaul is almost impossible to envisage, let alone implement, and this has led to this very recent phenomenon of "god versus science" - a most ludicrous juxtaposition if ever there was one.

The end of god as a valid concept will come when it is seen to contradict something useful by the majority of people in the world, and this will only happen when recourse to knowledge and the ability to add to that knowledge is shared by that majority. In the meantime rational people must face the reality that they are in a minority, and that essential time and brainpower is being wasted - even by them - on an outdated and increasingly less useful stop-gap in terms of species survival.

I like an explanation I heard a rather long time ago about the creation of the universe and the answer to theists question "Why is there something rather than nothing".  Zero is very difficult to maintain, and so reality fluctuates between the negative and positive.  I have no idea if this could be so, but it seems poetically simple. Nothing has a very hard time existing, so to speak.  I imagine an endless abyss with 1 and -1 where as you slip down the walls of the canyon you get to .01 and -.01 and deeper still .001 and -.001, the decimal slipping back again and again endlessly... never reaching exact zero.  However that's how I imagine it, you can obviously see I'm no scientist.. just a dreamer that seeks more than the bankrupt theisms can give.