Mark Kleiman is right, the commentary on the Pew torture poll is producing a lot of faulty analysis. The religious demographic traits that align with torture also align with other factors, such as education, region, race, and political affiliation. After all, in the present time, White Evangelicals are much more Republican than the population as a whole, and Republican leaders are more supported of torture; therefore, it shouldn't be that surprising that White Evangelicals are more supportive of torture.
That said, it's worth pointing out that a certain subset of American Christianity has in the past had a similar ends-justify-the-means attitude when it comes to the treatment of outsiders (and let's be clear, when a pollster says "suspected terrorist" most of the country hears "swarthy brown people"). Looking backwards, nineteenth Century efforts to "civilize" Native American populations involved a lot of what we would today call immoral behavior in the name of God. And while a number of Northern churches were the center of the abolitionist movement, the presence of slavery in the Bible was used to justify the "natural order" of antebellum times. A lack of concern for non-believers isn't unique to Christianity, as the residents of the Middle East or Kashmir will tell you, but that doesn't mean it doesn't exist.