Your are correct that as objectively formulated ID doesn't posit a specific deity... Christianity, Islam, or even Jefferson's "Nature's God" would fit the bill. But they all appeal to the super natural, and hence are religious versus scientific.
And while ID isn't objectively Xian, read the judges opinion for very substantial evidence that at least in the Dover case, ID was used by Xians to further what they consider Xian ends.
http://www.pamd.uscourts.gov/kitzmiller/kitzmiller_342.pdf
Exactly how does organized matter, intelligence, and design, "appeal to the supernatural?" Granted, many religions posit God as Creator and Sustainer of the universe. That only means intelligent design happens to be compatible with a religious understanding, and yes, that compatibily easily extends to a specifically Christian point of view. So what?