the people i'm discussing hold absolute views on a limited issue. it's black or white, not grey
I don't know what this means and it doesn't address my point.
so logically it should be considered very immoral to lie about this
No, that does not follow from this: "religious language and notions of the sacred, etc. go hand-in-hand with political community"
if he doesn't believe in god, but claims to, then you're wrong. belief in god has nothing to do with the end (policy). he lies about a completely unrelated topic as the means to that end
No. I accept a couple of premises here that may clear things up. First, American civil religion entertains a vague notion of God--God bless America, American providentialism, etc--that isn't necessarily beholden to any particular religious confession but is generally related to Christianity. Second, American civil religion is not a means to the end of some particular policy.
Third, rhetoric or the manner of persuasion in general is not necessarily a means to an end of some particular policy. So for instance, it's not clear to me that principles of Christian charity are means to the end of policies like medicare or Obama's ACA. We appeal to those principles because they persuade people to adopt these policies, but we also desire these policies precisely because we hold these principles.
Fourth, it isn't clear to me that, based on what Obama has said about religion, that we can call him a "liar", or that we can say that he uses religion as a means to an end. He could just have a different interpretation of religion that aligns it with American civil religion in general.
So to take the example of Romney again. Romney is a mormon, and generally we could argue that "orthodox" Mormonism does not believe in the separation of church and state. But Romney expressly keeps his confessional beliefs outside of policy, and generally only brings religion into policy in the most general, civil religion sense. Does this mean he's a liar? What if he really believes that the best government would be a kind of theocracy a la Brigham Young? Would that make him a liar? Or if he doesn't believe that, does that mean he's lying about being a Mormon?
I don't think so. Now, if Romney, upon being elected president, suddenly announced that he was going to govern according to the principles outlined in the Book of Mormon, or by the example of Brigham Young, I would say that he had been lying in the bad sense while he was campaigning. But it seems to me that Romney probably had his own way of reconciling his public statements with his inner-most religious beliefs. I don't think for the purposes of politics we should care or demand to know exactly the ins and outs of his own reasoning on this subject.
lying to other counsel or a court can get us sanctioned/suspended. we have rules about this
if we lie to a judge, there are severe consequences, both ethically and in terms of practice
Of course, but is there not quite a bit of gray area as to what constitutes lying? I.e., isn't there a difference between what would count as a lie in the eyes of the law vs what we call lies in everyday life? And what about "lying" in business transactions? Seems to me there's an analogous sort of slippage.