The whole point of having a jury trial in the first place is that the prosecution files a charge of specific wrongdoing and then tries its best to prove it with evidence that has been screened to keep out the worthless (or too damning, or unconscionably obtained) stuff.
This lets the defense have a fair shot at holding up the evidence to the light of day before twelve good men, and women, and true.
Then the judge instructs on the relevant legal principles, the attorneys argue, and the jury goes into hiding to deliberate and order pizza, not necessarily in that order.
Juries are told they may not flip coins, cast lots, perform experiments, look up words, or discuss the case with anyone, (including spouses, kids, friends, clergy), or even among themselves unless all twelve jurors are in the same jury room together.
We expect them, as the conscience of the community, to use their best judgment, their individual sense of morality, in weighing evidence, deciding whom to believe over another, etc. Juries are told that the word of a police officer is to be given no greater weight simply because he is a police officer. All who testify are to be judged by the same standard, the rules of evidence. Of course jurors are encouraged by both sides to use their common sense. The DA says that common sense will tell you that the officer is telling the truth, while the defense argues that common sense will tell you that police officers suffer from the same human weaknesses as the rest of us.
Such conflicts and other dilemmas are enough to drive some jurors to religion.
Suppose you had the fate, the life, of a young defendant in your hands as a juror, and you were unsure of your own feelings. What do the leading moral lights have to say about the death penalty? What do the biblical authorities have to say about putting an errant boy, as you see the defendant to death?
Why not pick up that Bible you keep next to your bed to see what God has to say about such weighty moral questions? Is it wrong to consult the Bible?
Was the juror relying on the law given by the court? Or the law given by God? Was the juror resorting to a higher law? Whose law decided the young man's fate? The State? Or the Lord?
Suppose the juror didn't actually open the Bible, but remembered a passage from it, such as "Thou shalt not kill," or "Judge not lest ye be judged?" Would the prosecutor have a right to be upset if the juror later said that if left to the juror he would have voted in favor of the death penalty, but those passages which he remembered, or looked up specially for the occasion persuaded to vote in favor of life?
Would the defendant and his attorney have a right to be upset if the juror voted in favor of death on the theory that his, or her, Bible fell open to the passage that states: "An eye for an eye, a tooth for a tooth," or "Render unto Caesar what is Caesar's, and unto the Lord what is the Lord's?"
The reason for all this, of course, is that the Colorado Supreme Court overturned a death penalty because a juror consulted a Bible. The N.Y. Times article (3/29/05) appears below: