For decades, the central argument in the debate on the legitimacy of homosexuality in modern society was informed by the Bible in this secular country. Christians made common cause with a diametrically opposed belief system -- Judaism -- to point out that in Leviticus 18:22, their respective deities condemned homosexuality.
In fact, the common cause isn't as common as many people think. More politically liberal rabbis, not having the luxury Christian theologians have of saying "that's a discredited precedent" (because there's no Jesus to say "that was before me"), have at least since Stonewall been looking for ways to read the passage as something other than a blanket condemnation of male homosexuality or male-male sex.
For example, there is a school of thought that says the Torah was only talking about its own time, and it's only a sin if it's unnatural. In other words, in our modern understandng a straight man shouldn't have sex with another man, but a gay or bisexual man may. This strikes me as a little post-hoc. Another interpretation is that the word used refers to a power imbalance. Male-male sex for love is acceptible, but prison rape is right out. This doesn't, however, make heterosexual power imbalances necessarily fall under the same prohibition.
However, here's BZ's take:
Therefore, just as a man is forbidden from having sex with his mother, his sister, or a married woman, he is also forbidden from having sex with his father, his brother, or a married man.
His reasoning may seem a little arcane, and for reasons he gives in the comments it's not going to fly with the most fundamentalist Jews any more than it will with fundamentalist Christians. However, it seems to my non-expert eyes to be a validly-arrived-at reading of the passage, and one that could, culturally, have been intended by the original author (or Author).
One of the obstacles to my classifying myself as a Jew -- or at least as a secular Jew rather than a Jewish-raised secularist, which is largely a perceptual shift -- is that I find my political and ethical beliefs, which are deeply held and, I feel, rooted in good things like justice, seem to conflict with readings of Jewish law. It'd be nice to be able to resolve this.