Evolution is a theory. But that doesn't mean it isn't true.
A theory is something that explains facts. Of course, you might be talking about the "I have a theory" bar version

.
Add on: since we all seem to link to the Atheist Experience nowadays...
Eee, you missed the point. Evolution is a fact, "evolution through natural selection" is the theory. In terms of the video you posted, it's like "gravity is a fact and 'theory of gravity' explains how it works".
Did you read what I said before? This 'we don't do theology' bit is far too convenient a dodge. Any time a more sophisticated argument is raised, and you don't have a slick and easy answer for it, you just have to say "that's a theological question", and thus avoid having to give any answer at all.
Oh yes, I did read your response. My answer was included in the response to Masada.
You're talking about sophisticated theological arguments. The problems I see with these arguments is that they're based on the same thing the whole theology is - the existence of God. Until this assertion is proved, it makes no sense to discuss anything else theology has come up with.
Many atheist thinkers have engaged religionists over such matters, and more often than not the former have come out on top. So it's not like we're talking about debates where the result is already decided in favour of the religious types.
Oh yes, many atheists - usually deconverted Christians who have previously studied Christian theology a lot - are able and willing to enter the swamp with the believers and defeat them on their own battleground.
Other atheists, like Dawkins, choose a more scientific approach to the discussion and for their line of argument, theology is virtually irrelevant.
It seems to me that Dawkins, while quite adept at preaching to the more militant part of the atheist choir,
Oh no, stop right there. "Militant atheism" or "fundamentalist atheism" and so forth are just denigrating labels assigned to vocal atheist by believers. Questioning a belief isn't sign of militancy. Criticim of an idea or doctrine isn't militancy. What Dawkins is doing is as far from "militant" as it can possibly get.
I guess he's labeled so because of his willingness to go into open confrontation with believers, openly criticizing their beliefs. But this doesn't make him militant or gods-forbid fundamentalist.
either lacks the wits or the guts to take the religionists head-on in such a manner.
No, he simply doesn't see the need to disprove all of theology, because that would mean he voluntarily accepted the burden of proof. In fact, this burden of proof is on the believers who need to prove their basic assertion of God's existence in a scientifically verifiable way. Until they do that, there is no point in getting dragged into theological discussion.
The "Courtier's reply" analogy explains it pretty well.
Moreover, it's actually quite reasonable to consider what would be the case if a given argument were true. Indeed, this is what happens when we make and test a hypothesis. In this case we might take the competing hypotheses to be (a) that gods are just figments of collective imagination, and (b) that God/gods have some existence independent of the imaginings of them. Both are reasonable notions, each of which can be made to fit with the evidence at hand, and neither admits of any hard proof. To my mind, the former is a far more likely to be correct, but that does not justify dismissing the latter out-of-hand.
This is not the way atheists discuss the matter. Atheists simply refuse the theists' hypothesis and their arguments is simple - theists don't have anything at all that would confirm this hypothesis, ergo it is not rational to believe that this hypothesis is in fact correct.
Some atheists go further and speculate about why people invented God, or why they believe in God, what motivates them, how the idea of God spreads etc. etc. etc. For all this, they need evidence, working theories, models, experiments and so on.
But they need none of this if they simply refuse to believe in the original theistic hypothesis.
Besides, Dawkins has shown himself to be quite prepared to engage with theological arguments when it suits him - that is, when those arguments admit of an easy refutation. For example, he has no issue with confronting the classic 'argument from design', which rests upon a quite specific idea of God as creator, and has always (to my knowledge) fallen under the theology umbrella.
He's doing it in case of the most widespread myths and false notions which, in his opinion, are harmful to the society. For example, he confronted I.D. and similar nonsense because it is trying to pose as science, which Dawkins as an evolutionary biologist finds outrageous (rightly so). He confronts religios education at schools on the basis that it is essentially a form of child abuse and unacceptable indoctrination with irrational ideas which is harmful for children.
I really don't see how this is relevant to theology and its relevance.
That the argument was neutered to the point of being irrelevant some 200 years earlier, and is given short shrift by any half-decent religious thinkers today, doesn't seem to bother Dawkins at all. It's an easy target, so he plays to the crowd by making a big deal about knocking it down.
It's actually not such an easy target, because otherwise there would be no such fuss about it. In the US and some other parts of the word, these absurd notions of creationism are gaining momentum and Dawkins wants to push them back where they belong. And I wholeheartedly support him in that.
I should also add that Dawkins' case is not merely that there is no proof of gods' existence, nor even that the evidence fits much better with the non-existence of a god or gods. Rather, his aim is to demonstrate that belief in god(s) is irrational, massively harmful, and thus should be brought to an end.
Which is only a logical extension of the first conclusion, that faith without evidence is irrational. The debate about how dangerous religion is in practice is merely a follow up. IMO it would be more hypocritical to say
"we've established that you are wrong about you beliefs which are irrational, but we won't try to educate you and explain to you why are you irrational beliefs potentially harmful".
Dawkins started this whole discussion precisely because he wanted to stop religion from undermining what he sees as the basis of modern secular society - rationalism, scientific progress and enlightened morality.