If there's no good evidence for the god hypothesis, then where did it come from? What purpose does it serve? Why do people keep believing it?
I'll answer these questions briefly and in order.
I think religion is a by-product of two different drives. The first is general to all thinking creatures (ie. most animals), the second isn't specific to humans, but has definitely found, I suspect, its greatest expression in humans. The first is that we learn, the second is that we teach.
I don't know that all animals learn; sponges and other brainless animals certainly do not. At least one researcher believes the primary purpose of the brain is movement, and other purposes are all secondary. I'm not sure I agree, though he makes a compelling argument. However, one of the things our brain does is allow us, and many other species, to learn. We are pattern-seeking creatures, we seek to master our environment, we want nummy candies and to win in fights and to get laid and all the other things that will help see to it that we have grandchildren (which the first step to evolutionary success).
To that end, we can become addicted to gambling and coffee.
Actually, that's an unfortunate by-product of the learning process. If you know someone who loves his coffee in the morning, you may notice he has a certain way of doing things. It has to be a certain brand of coffee. A specific flavor, region, roast... He might grind it himself and prepare it in his own little French press. He definitely, no question, has his favorite coffee mug, and probably drinks it at a certain time of day; usually it's part of a larger set of "getting up in the morning" rituals.
One of the things caffeine does is short circuit the part of the brain that lets you know you've won. Whether it's a good grade on a test or solving a puzzle or getting a new iPhone, you know that feeling when part of you lights up and does a little happy dance. Of course, a week later that test is crumpled up on the floor of your locker, the puzzle is in the recycle bin, and your phone is no longer to be carefully placed on its own altar on your dresser, but to be thrown casually onto the bed with all the other crap in your pockets. That feeling goes away because you need to move on to the next challenge, figure out the next thing, master your environment more fully.
Caffeine cuts right to the chase and gives you that happy without having to actually solve, win, or buy anything. Your brain, trying to figure out what it's won at, just randomly attaches importance to whatever's going on when you get your buzz on. Over time, the importance accumulates on things that stay the same: the time of day, the kind of coffee, the coffee mug, the way you prepare it... All of these things become important to you not because they actually make the coffee better, but because your brain has been wired to say WRONG if any of that changes. What was a valuable learning tool has been totally screwed by chemistry.
And gambling? That learning process is meant to find patterns so that we can take advantage of them. Dice don't have patterns, so our system goes completely haywire and, again, starts attaching undeserved importance to meaningless rituals. That is to say, gamblers are superstitious because their brains are on their metaphorical knees, crying their metaphorical brain-hearts out. Okay, that's just why gamblers are superstitious. Addiction is more complex and has to do with the fact that losing feels much more bad than winning feels good. As with any other addiction, you do it not because it feels good but because it feels bad when you don't. How good does it feel? The more certain something is, the easier it is to figure out and the less incentive their is to master it. I'd venture a guess that the most popular games at casinos are very nearly 50/50 odds (played correctly, craps and blackjack are, I'd say that, in the long run, so are competitive games like poker).
Anyway, we aren't the only creatures to develop superstitions in the face of an uncontrollable and somewhat random universe. Psychologist B.F. Skinner discovered that pigeons, given food at regular intervals with no reference to the pigeons' behavior, quickly developed superstitions regarding what causes food to drop. Lest you think, "Well, pigeons, yeah, they're stupid. Terry Pratchett said so." and believe yourself immune, more or less the exact same thing has been observed in humans in Dungeons and Dragons Online. Players rapidly conceived the belief that using a certain skill absolutely improved the loot dropped from treasure chests and could not be dissuaded from that belief (note: they were wrong). When the developers made it impossible to use that skill on treasure chests, there were massive fan complaints that their skill had been rendered useless.
In the face of a large and uncaring world where small mistakes can cause massive dying, superstition was and is inevitable. We are all of us autodidacts to a degree, and we all develop these silly habits. Thus learning can make fools of us all.
What about teaching? Animals teaching their young has been observed in the wild, but nowhere to the degree that it's found in humans. Compared to pretty much any animal you care to name, we are weak, blind, and deaf. We might as well not have noses, and our teeth and claws are a joke. We are completely helpless for several years after birth, and our maturation process is an incredibly protracted part of our lives. How the hell do we manage in a dangerous world? By passing accumulated knowledge from one generation to the next. Far more than any other creature I know of, the human animal passes knowledge from one to another. Long story short, if our children didn't listen to us, credulous to a fault, it would be much, much more difficult for this to happen. And, yes, I mean that literally; children are credulous to a fault. They'll believe any damn thing you say.
What this means is that children, lacking critical thinking skills and, I believe, primed to believe everything they're told, absorb their parents superstitions as readily as their hunting skills, their knowledge of interpersonal relationships, and how not to poop in your food.
This notion has spawned the study of memetics, essentially a branch of information theory that might be considered an analog of biological evolution, where ideas and information travel through their space (inside our heads) and warp and mutate based on a much more loosely governed analog of genetic evolution. Think of it this way: a good idea, how to make a really awesome spear, say, maintains itself because deviations make the spear less effective and its demonstrable efficacy discourage deviations; a bad idea, like repeatedly stabbing yourself in the balls to control the urge to masturbate, weeds itself out because it's demonstrably not effective, and anyway masturbating's not actually a bad thing; a neutral idea, like turning around three times and spitting when you jinx something, can just hang around and mutate and warp because it doesn't have any impact one way or the other. After all, since there's no such thing as a jinx, whether you turn before or after you spit doesn't make much difference. Though the schism and five generations of bloody warfare between the preturners and the posturners were quite hard to watch, and let us not speak of the genocide of the widdershin turners by the sunwisers.
Thus it's quite easy to see religion as another superstition and the result of thousands of years of memetic evolution, an evolution that continues today as sects split and diverge and merge and mutate. Whereas most superstitions hang on just because and we don't necessarily attach much importance to them and really belong just to the individual (like the unfortunate ball-players who neither change nor wash their underpants...), religion is a collection of self-supporting memes. It piggybacks on the morality of sanctity by forbidding the questioning of ideas, on on in-group loyalty by providing visible markers of kinship. It produces an internally consistent structure with little or no external reference, nor much need for one. When it does impinge upon the outside world, it but co-opts other learning (societies that were originally pastoral show it in their myths wherein they hate farmers, see Cain and Abel. Societies in arid countries all hate pigs, which require lots of water. Populations prone to bee allergies learn to despise honey.).
In short, modern religions are crude amalgams, a cobbled together attempt to understand and explain the world consisting mostly of superstitions, the crude xenophobias of the world in which they were born, and occasionally useful rules of thumb from bronze age culture. Useful only in a bronze age culture, mind.
Okay, so much for talking briefly. That's where religion came from. Next, what's it for?