"Anyway, was Europe a haven of peace when it was all united under the Church of Rome?
Personally, I'd have thought that trade was a fairly significant factor uniting different tribes. When communities specialise in one or other form of production, perhaps initially for reasons of geography, and later by tradition, and they can mutually benefit by swapping objects, then they can become worth more to each other alive than dead."
World peace didn't happen under non-religious regimes either... the point is that we are slowly forming larger and larger social groups. Tribes were united by religion, then they formed nation states, which also proceeded to try to kill each other, major world wars, and so on, and now we are trying to unite nation states into some sort of planetary unity, the united nations being one of the first (and failing) attempts to do that. Would you say that we should abolish nation states because they have caused millions of dead in the space of a few years? No we recognise that the social grouping is large and allows industry and commerce on massive scales.
I'm not saying we're wrong to go beyond religion, just that for many parts of the world that are still feudal, like Pakistan, Darfur, and so on, religion is actually a step up for them, and guess what, religion is very popular in these places, because that's just what the people need and want. We as westerners have to be careful not to imagine that these parts of the world are just like us... I've lived in africa, so maybe it is easier to see.
For example, there was an interview with some women folk in a village in an african country that was about to get its first democratic vote. They asked her whom she would vote for to be president, and she said that her tribal king was the leader so he should be president. She would not accept as president any other tribe's king. We in the west are so far removed from that mentality, and our own history, that we find it hard to imagine how anyone would think that way--but just go there and find out. Likewise female circumcision. It's not something invented by religion, it is much earlier, it is a tribal thing. There are parts of africa where the christian missionaries complain that the locals are not rational enough, because they are still going to the witch doctor. Imagine that, a christian missionary complaining that the locals are not rational enough.
Trade is all very well once you have peace between tribes. As soon as difficulties arise, the tribal loyalty and blood lines resurface with a vengeance... Darfur was a massive tribal blood bath.
You need stable nation states united under one god before you can even begin to wonder about world peace between nations. Going back to Dawkins, he just doesn't know this stuff so he continues his anti-religious diatribes, sitting in the comforts of his safe British nation state, where we have government sanctioned tolerance between races and food on the shelves. It's fine to detest religion, once you are past needing it yourself. It is wrong to try to demolish it though, as it is a necessary step in many parts of the world. Demolish it and you just leave people at the tribal level, and that is closer to nature, and closer to the monkeys, who often kill each other's babies by bashing heads into rocks, to protect blood lines.
Sorry this is a long comment but it needs some examples to get across.