When we pick juries in my state, we are given juror forms filled out by members of the jury pool, what used to be called the venire. Rarely if ever do I see one with a blank in the religion block or "None" or "No Preference." (One might be pressed to inquire of the latter, "Does that mean you shop around?") But that is the point: judges are notoriously uncomfortable with extensive voir dire (jury questioning, the word meaning, in French, roughly "to tell truth"). As it is, attorneys preface any such inquiry with the promise, "We don't mean to pry," but of course that is precisely what is going on.
As Dean Pound said, experience is the spirit of the law. From past experiences I can say that when one reads this or that sect or faith in the religion block of a juror slip, one knows this person cannot judge because the Bible says "Judge not lest you be judged." It does not take a professor of logic to point out the questions begged by such an admonishment, but I know a non-judgmental type when I see one. Some wags point out, "Wanna bet they are entirely judgmental about their neighbors' wild parties, alcohol use, and other matters."
It might be argued that religion should play no place in a jury trial. This ignores the fact that religion impinges on everything a person does, even if it is the well-known religion of no religion. Yes, Sen. Santorum and conservative columnist Kathleen Parker claim that secularism is a religion, and as a secularist, Obama violated church-state separation by telling Catholic hospitals they have to make contraception available to their employees. (Ms. Parker might want to read a little Nietzsche. Might open her mind a bit. Nietzsche said Christianity was "the worst catastrophe" to befall mankind.)
Some religious jurors might be suspected of a tendency to accept things on faith, thereby eschewing factual analysis, use of logic, but I am not prepared to say that religions play a role in deliberations beyond those Christian principles we're already hardwired to hold "sacred" (as in Bill of Rights sacred, no faith necessary). More civil cases are decided on equitable grounds than legal. Juries like to think they're reasonable and that they fulfill the role contemplated by Spike Lee when he titled one of his "joints" (movies), "Do the right thing."
In a criminal context, however, I am not so sure. Years ago, we had a local criminal defense lawyer who was famous for getting people off or getting them lighter sentences. In a nearby beach resort, a gay man was tied to his bed, beaten mercilessly, and left for dead by a younger man who stole his car, his money, and his credit cards. He was caught and the local lawyer took his case, whether retained or court-appointed I have forgotten. As is sometimes the case in the murders of gays, the defense was that odious thing called "homosexual panic." This now-debunked and, in some states, outlawed "defense" is really nothing of the kind. It posited that some men, attracted to others of their own sex, find themselves torn between desire and revulsion; caught in the dilemma, they sometimes panic and kill the source of their "gay" feelings: the victim. It was the gay murder equivalent of an "uncontrollable urge" that allows consideration of manslaughter). Juries around here were just that gullible at the time. Or uneducated.
It would seem to me that such a "defense" would wash only among similarly gullible, uneducated jurors (this was in the 90s as I recall). The lawyer played the P (for Panic) card from the gitgo. But do you think he hired a licensed psychiatrist or even a psychologist to prove his defense? Hardly, the "expert" was a former pathologist who had served as the county coroner for a number of years. He wowed juries by telling them about pathology results with the victims of just such mayhem as was involved here. And these homosexuals practice such utterly repulsive and unnatural lives, they-- (By now the prosecutor, presumably not asleep, jumps up and objects that the witness might be going a little outside his expertise.) Nevertheless, the pathologist describes homosexual panic, how it works, and how the person accused of murder probably was in an uncontrollable panic and could not at that moment help himself. The jury came back with a manslaughter conviction and a sentence of a few years in prison.
My point is, simply, we can never really know how much the religious beliefs and convictions of juries play in a case like this. There is the condemnation of the stoning offense in Leviticus and the condemnation of Jesus-inventor Paul in his letters. But both historians and anthropologists agree that the author of Leviticus meant temple prostitutes (usually gay males, mostly crossdressed) of rival religions, e.g. the Midianites, who might worship Baal or some other deity, and in any case the prohibition was more designed to ensure the fecundity of the tribe: greater numbers meant more protection from conquest. Similarly, Paul betrays in almost every gospel both homophobia (probably a projection of his own nature) and misogyny. But how do you voir dire a jury on that when your client is a stud hustler and the guy he killed an older gay male?
During deliberations, do juries bring Leviticus and Paul, or the xenophobic morality tale of Sodom and Gomorrah to their thinking? Presumably, the defense lawyer would seed the jury pool with questions about their feelings on homosexuality, and if a juror expresses a strong religious conviction against homosexuality, the lawyer would tell the judge to strike the juror for cause. Unfortunately, the judge might go ahead and let the prosecutor rehabilitate the potential juror, eliciting for example a yes answer to the question, "Could you put those feelings aside and follow the law?" This would force the defense lawyer to use one of his optional strikes, which are few.
How much religion gets into a verdict? I have no idea, but it bothers me. It may be that Genesis, Leviticus, and the Pauline correspondence play major roles in deliberations of this sort. A juror might be thinking, "Well, the guy he killed shouldn't have tried to force this man into being a homosexual." Or one might be thinking, "The Bible says homosexuals should be stoned to death, so I can't see what this guy did wrong." If the topic rears its ugly head in deliberations and, say, someone says, "I know what he did was wrong, but, hey, that guy was a homosexual forcing himself on the defendant," would the other jurors really do their duty and send such statements packing?
Would juries engage in another practice they are forbidden from, compromised verdicts. By this means, holdouts for one side or the other agree to vote the other way if this or that happens. Although strongly advised against it, some jurors say things like, "If you'll vote to convict on the lesser included offense in the jury charge, I'll agree to a longer sentence when we punish the guy." (In Texas, one elects to be sentenced by either judge or jury, except in certain situations.) So you get manslaughter and a few years in the joint. It's kind of hard to believe that if the victim had been heterosexual, there would have been a murder verdict, and the culprit might have pled guilty in exchange for 20 or so years' imprisonment. He can then have his panic attacks in the state penitentiary.