Is criticism of Islam necessarily racist? No. Islam is a religion, which must be adopted. It's not an ineluctable characteristic of any person, much less a biological characteristic used to denote "race". Those who label all criticism of Islam as racist "Islamophobia" go wrong on this point.
Can criticism of Islam be racist? Per se, no; much depends, however, on the intention of the criticism, which can be inferred from the context and framing, and from what's not being criticized. A criticism of Islam can be used with racist intentions. This is where Hallquist and the Christianist neoconservatives go wrong.
If you criticize Islam, but not Christianity, I have to ask, "Why?" The hypothesis that you're engaging in differential criticism on the basis of race is at least live and deserves investigation.
In Fitna, Geert Wilders criticizes Islam as a politician explicitly endorsing restricting immigration, especially non-Western immigration. Again, the criticism per se is not racist, but the framing and context of the criticism can definitely be racist.
(I don't know that Wilders really is a racist, or that Fitna really is in a racist context. I really don't care much about Dutch politics, and I'm already convinced that Islam is as monumentally stupid and hateful as is Christianity. But raising the issue is not, as Hallquist asserts, prima facie an "Orwellian lie" by virtue of Islam being a religion, not a race.)
Consider the analogy: Suppose I were to talk about crime, or tyrannical dictatorships, or ridiculous superstitions. In my talk about the topic, I show only examples of black people: black criminals, black dictators, superstitions held in African countries, ignoring white criminals, white dictators, white superstitions. And suppose, for instance, that I were using the discussion to justify differentially affecting the rights and privileges of black people. Even though all of my facts were 100% accurate, even though I'm not explicitly talking about race, even if I never actually mention the race of the people I'm talking about, I could still be justly accused of the most egregious racism.
There are ways of framing the exact same facts, of putting those facts in context, that are not racist. It would for example be a non-racist framing and context for a black person to discuss black crime, with the intention of trying to help members of her own community live better lives (and to criticize the egregious racism of defining specific crimes and punishments that differentially and intentionally affect black people).
We are in that awkward stage regarding racism where explicit racism is almost universally deplored, at least in public, but racism itself is obviously (a few obtuse neocon fuckwits excepted) still around, still strong. Thus racists have to put a veneer of non-racism around their racist propaganda; they have to resort to implications, context, framing, dog-whistles and other forms of obfuscatory bullshit, while explicitly saying, "Racism? I don't see any racism. Nope, no racism here, by golly! wink wink"