I don't follow Derbyshire but I was trying to follow this thread. I don't see how the statement you quoted leads to him being a militant atheist.
Okay, I can see how someone might not. In point of fact, I wasn't calling Derbyshire a militant atheist--- I was just saying that if someone were to interpret his comments as being from a militant atheist, that person would not be making an unreasonable interpretation.
The key to the above quote is that Derbyshire says that he believes that Christianity is either false, metaphysically speaking, or that the metaphysical concepts concepts it talks about are irrelevant to modernity--- that is, to us. The key is when he says "even taken in their most general interpretation." That last is a very absolute statement, the sort which is consistent with a strong position such as atheism.
As for the the "militant" part, that was supported not by that quote, but by by what I described as Derbyshire's tendency to attack the metaphysical, epistemological and meta-ethical foundations of religion and morality (which has of course been traditionally linked with religion). He does so because he thinks religion and morality are essentially arational-- that is, not being being products of rational thought, they cannot be negated or undermined by rational thought.
This means that Derbyshire ends up usually making the same sorts of arguments one reads at infidels.org and other atheist web sites. But what really makes Derbyshire come off as "militant atheist" like are his arguments about the place of religion and religious morality in the public square. He's against them. Not Christmas displays and other forms of religious symbolism, but the sort of stuff that goes beyond mere symbolism.
For instance, Derbyshire characterizes right to lifers as religious fanatics; the best he can muster about them is that "Even cults have a right to be heard. I would not like to see RTL views prevail; but I would rather see them prevail than see them stifled." He also believes that "our Constitution does not permit the framing of laws based on the peculiar tenets of any religion." Well, it hardly needs saying that the Constitution does no such thing--- there is nothing in the Constitution that prohibits laws that make liquor stores be closed on Sunday, for example, even though blue laws are rather obviously religiously inspired. Derbyshire's interpretation of the Constitution, however, does happen to be the same as that of Michael Newdow-- who virtually defines the term "militant atheist"-- in this instance.
Now, as it happens, I believe Derbyshire not to be an atheist, because he's written that he's not, and for me that trumps the above, but I wasn't trying to be insulting through insinuation or anything like that. My point was simply that for someone to interposer him to be a militant atheist based on the fact that he thinks the pro-life movement is freakishly cult-like and believes in the naked public square in which religiously motivated arguments are prohibited, is not a case of that person making an unreasonable interpretation. The same sort of different interpretations are reasonably made of Hume, who he admires and in many respects emulates. I hope that helps but I'd suggest you read Derbyshire to get a sense of what I'm talking about if it doesn't. From looking at your posts (you're right, Cher sucks!), I get the impression you might enjoy his writing, although I have no doubt you would take issue with a great deal of what he says; Derbyshire takes pride in being a contrarian and generally ensures there's never too many people too happy with him (including me-- but that's not to say I don't learn things from him).