Having written this, I just reread the rest of the thread and noticed that what I say has already touched on by Clive. But it's necessary to keep in mind the idea that religion flows out of an alienated, exploitative society - both as consolation for the exploited and oppressed and an 'explanation' of why humanity's enormous and increasing technical power has not resulted in a rational, harmonious world. If you do, you see clearly Dawkins' one-sidedness.
I can't remember the exact reference, but early in the God Delusion, Dawkins basically says 'The world is a bad place - live with it'. If you think this, it's easy to see why you'd sneer at religious people. (Dawkins' approach smacks to me a little of 'Why can't everyone be an educated sophisticate like me?')
Marx's approach was (of course) more subtle:
"Religion is, indeed, the self-consciousness and self-esteem of man who has either not yet won through to himself, or has already lost himself again... Religious suffering is, at one and the same time, the expression of real suffering and a protest against real suffering. Religion is the sigh of the oppressed creature, the heart of a heartless world, and the soul of soulless conditions. It is the opium of the people... The abolition of religion as the illusory happiness of the people is the demand for their real happiness. To call on them to give up their illusions about their condition is to call on them to give up a condition that requires illusions... Criticism has plucked the imaginary flowers on the chain not in order that man shall continue to bear that chain without fantasy or consolation, but so that he shall throw off the chain and pluck the living flower."
(A Contribution to the Critique of Hegel’s Philosophy of Right)
This is doubly and triply important to understand when a majority of religious people are not just deluded individuals to be argued with, but members of our class who we want to struggle alongside, in some cases putting the needs of the class struggle at least temporarily above the struggle against religion.
So as a scientific explanation of why religion is nonsense, and a rousing shout in defence of atheism, Dawkins is great. But for socialists he's fundamentally one-sided.