I agree with you entirely on Dawkins et. al.  I continue to be amazed (uh, recent events notwithstanding) at how many otherwise intelligent people can fail to realize that haranguing someone is not a great way to change his or her mind, but just makes them dislike you.

Now there will always be segments of the religious community who cannot "play well with others" but at the same time it is important not to make atheism a pre-requisite of being a progressive, IMO.

I think that's a very important point, and it's one of the reasons why, despite being non-religious myself, I joined Street Prophets as soon as it was launched, because I thought it was really important that such a venture be successful.  As someone who is not religious, who comes from a country where the dominant political discourse has become very, very religious -- and more explicitly, very, very Christian -- my view was that the only way to negate religion as a political tool is to make it basically something that doesn't give one side or the other an advantage.

That plan could, of course, backfire, and just contribute to the overall Christianization of U.S. politics, but then I don't know what to do.

I very much personally support the notion however that one thing progressives could usefully do for themselves, but also for civil society is build a social support system and set of communities that isn't based on religion but gives people a community to anchor in.

Yes, I support that too.  And in a way, that's sort of what (I feel) we're doing here at ET... sometimes more successfully than other times, but that's how things go.

but at the same time it is important not to make atheism a pre-requisite of being a progressive, IMO.

There is absolutely no fear of this happening at all. On the other hand the left could cut off its nose to spite its face and the religious progressives and the atheist progressives could never speak to one another except to hurtle insults.

As mentioned in a different response - think of people like Dorothy Day - and lets add Martin Luther King.

_{aspiring to genteel poverty}

I found Dawkins far more sympathetic after reading his book: The god delusion. It was quite funny, I though. And I though he made some very good points...
For example: We have all these religiouns more or less explicitly claiming to be the Truth, which means they think the other ones are Wrong, and this is more or less okay. Making a similar statement, the Athiest is accused of smug superiority and of being condescending and patronizing. Unlike say Catholics, we do not condemn people to an Eternity in Hell for disagreement. Now, the Catholic position seems the rather smugger one to me, assuming as it does an eternity of suffering for those of other or no faith.
(Possibly the religious know something (ie. us Athiests are Right) and are just unhappy to admit it, and hate to have it pointed out? Why else would this be such a sore spot for them?)
No, atheism should never be a prereq for a particular political direction. But I see no reason why Faith and Religion should be these great Untouchable subjects about which we are not allowed to make disagreeing statements but must proceed with uttermost care and delicacy and tolerance or feelings gets hurt.