It's hard to see religion as "tertiary" to intelligent design when the concept was invented by Christians to make their religious beliefs sound more scientific. Hell, the first thing that came up when I googled "dependency graph of life" was an article from a site owned by the Discovery Institute, an organization founded to promote conservative Christianity. Berlinski also works for them.
There are certainly a large number of Christians involved in the intelligent design movement, many of whom are quite likely involved because of the perceived religious implications. But, for that matter, most of the founders of modern science were Christians, who often came up with their theories as part of apologetic arguments they were working on. If we were to dismiss all scientific theories invented by Christians for that reason, there wouldn't be much left to modern science, or mathematics for that matter.
However, it is possible to separate the theories from the apologetics, as mainstream science has done.
The Discovery Institute itself is run by a mix of atheists, Jews, Catholics and Protestants. All whom are involved because they think there is a real scientific problem. Many of them do use ID to further argue for religious conclusions, but the theory itself is religion agnostic, and is also compatible with atheism, as demonstrated by the atheists and agnostics involved.
I would suggest you not dismiss the theory itself merely because of your dislike for the religion of many of its proponents. Doing so is the genetic fallacy. Additionally, some of the earliest proponents of ID type arguments, such as Paul Davies and his fine tuning argument, are not themselves Christians.
