I've been hearing about people who are upset at the news that an incoming Congressman is being sworn into office on a copy of a Superman comic book. People are suppose to swear on a copy of the Bible! they say.
Actually, swearing into office in the U.S. doesn't have to be on anything, and while presidents are usually inaugurated on a personal or family copy of the Bible, legislators are just as likely to swear on a copy of the Constitution, which is after all the document they are swearing to uphold.
And in fact, if you read the full news story, Congressman Garcia is swearing on a copy of the Constitution, and underneath it he is placing some mementos of personal significance to him, including that Superman comic, his citizenship certificate, and a photo of his deceased parents. I think that puts it into proper context.
But this raises the question of non-Christians (I don't know Garcia's beliefs) swearing on a religious text. Why does a Christian swear on the Bible? That sounds like the setup line to a joke, but I presume it's either because 1) the Bible is holy and meaningful to you, which is why you might specifically use a copy of it that's personally meaningful to you; or 2) you're invoking the authority of God to strike you down if you fail to abide by your oath.
But by either account this would not apply to non-Christians. If the Bible isn't holy or meaningful to you it would be hypocritical at best, sacrilegious at worst, to swear on it. (I refer you to C.S. Lewis's castigation of himself in Surprised by Joy for having taken communion as a youth at a time when he was secretly an atheist.) And if you don't believe in God it means nothing in terms of verifying your sincerity to swear may He strike you down if you violate your oath, even if Christianity is true and He will.
I'd also like to point out that when Tom Sawyer and Huck Finn want to swear a solemn oath, they prick their fingers and write their initials in their own blood. The Bible doesn't mean much to them.
I turn back to Keith Ellison, the first Muslim (I think) to serve in Congress, who was sworn in on a copy of his religion's holy book, the Quran. And for a copy meaningful to him - meaningful, please note, as a U.S. public official - he asked, as was his right as a member of Congress, to use the Library of Congress's copy that was once owned by Thomas Jefferson. This story interested me at the time because the L.C. rare books librarian charged with carrying this volume to the Capitol had worked at the Stanford library when I was also there, and I'd met him.
A Jewish person who wishes to swear on a religious text would pick the Jewish Bible. In my case it'd probably be the copy of the 1917 Jewish Publication Society translation (there's a more recent translation, but it didn't exist then) that I was given for my Bar Mitzvah. (B. pointed out that, if we're choosing for personal meaningfulness, that I could swear on a copy of The Lord of the Rings. I'd have to think about that. It is true that, when we had our photographic portrait taken and bringing along something to hold was suggested, I took a collector's edition of The Lord of the Rings and B. took her violin.)
I'd also like to bring up the question of terminology. The Jewish Bible is, allowing for differences in translation and canonicity, what Christians call the Old Testament. No surprise, the Jews don't call it that. Among ourselves, Jews of at least my persuasion just call it the Bible, because we know what we're referring to. When we need to specify it we use the Hebrew word, which is Tanakh. What Christians call the New Testament, or both together, Jews refer to as the Christian Bible or the Christian scriptures.
While I'm at it, two more Jewish religious textual terms which may confuse others, Torah and Talmud. The Torah, specifically, is the Pentateuch, the Five Books of Moses. A Torah scroll is the Hebrew text of this, hand-calligraphed onto a roll of parchment, and these are the holiest objects in practical contemporary Judaism. But the word Torah may also be used to refer to the body of Jewish religious law and tradition, which includes but is not limited to Tanakh and the Talmud. The Talmud, which is very much longer than the Bible - a copy will take up at least a whole shelf - is a series of nested commentaries on Biblical commandments and practices, compiled by the early rabbis in the early centuries C.E. I will spare you any discussion of its versions or constituent parts, for which you will thank me.