As a Jewish Conservative (and a Conservative Jew), I see things very much as evangelical Christians do when it comes to moral and social issues. I’m less enthusiastic about the strain of anti-Mormonism that I’ve seen around here, which to me is maybe a little too close to the kind of Antisemitism that I experienced as a kid.
Christianity is theologically black and white, or at least the kind that uses the bible as its chief reference and argument settler. That’s a separate issue from social mores, a place where I’m not even going. As I mentioned, there is little room in Christian theology for “this person was worshiping a genuine God, but in confusion and error,” unless that person is a relatively new Christian, or a special case like the Greeks who actually did create a monument “To An Unknown God” (the back story is that this was indeed in reference to an event brought about by prayer to the God of the Jews). Mormonism is theologically frowned upon in Christian circles due to its accretion of extrabiblical bogosities through Joseph Smith. It’s commonly held in Christian circles, and I believe it is for good reason, that Smith’s revelations weren’t confused divine ones; they were devilish.