For men swear by one greater than themselves, and with them an oath given as confirmation is an end to every dispute.
Hebrews 6:16

For when God made the promise to Abraham, since He could swear by no one greater, He swore by Himself
Hebrews 6:13

What is the significance of God swearing and having to swear by Himself?

On the other hand, we might know for a fact that someone’s beliefs are wrong, but the oath might be valid nonetheless. A judge might say to a child on the witness stand, “You know about Santa Claus, don’t you? Well, then, you know he’s watching. And you’re gonna be a good little girl and tell us the truth, even when it’s hard, right?” I don’t support this practice, but I have to admit that our society makes Santa’s presence very real to kids. A kid who believed in Santa might find this talk a strong encouragement to tell the truth. And if the judge needs the kid to talk about stuff that the kid really doesn’t wanna discuss – witnessing a murder, or sex abuse – a judge may be grasping for ways to encourage cooperation. Eternal damnation in 70 years may be a hard thing for a kid to fathom; coal in the stocking next December may be easier to grasp.

“Put aside the whole ACLU issue for a moment: What are we trying to accomplish by having people to swear to things that are meaningless to them?”

If I swear, I swear by One greater than myself. If I lie, I’m accountable to the One by Whom I swore.
It doesn’t matter if I swore using a Bible, koran or any other Holy book. It only matters to me and to Whom I swore to. My oath would be to One greater than myself.

If the testimony will save you from death-row, do you want me to swear by my God or someone else to testify and swear, who’s god instructs them to lie and kill?

Anyone remember the trial scene in “Fried Green Tomatoes” when a pastor is called to give an alibi to the (guilty) women accused of killing her husband? The pastor informs the bailiff that he had brought his own Bible to swear to. He then proceeds to lie. It is later revealed that he had brought the dictionary (or something) rather than the Bible to court that day. The suggestion was that he would have felt uncomfortable lying after taking an oath on the book that was so pivotal to his faith.

Of course, if a Hindu take an oath based on the Bible, is that any different to him than swearing on a dictionary? Wouldn’t we rather a Hindu swear to tell the truth based on something that was meaningful to a Hindu?

This is not a freedom of religion issue; it’s an administration of justice issue. An oath is not administered for the benefit of the person taking it; it is not an occasion for personal expression or evangelism. It’s administered for the benefit of people who need to know what the witness knows, even if the witness doesn’t want to disclose it. It is given in an effort to increase the stakes the witness will feel for lying. Consequently, I want a witness to swear according to whatever authority is most meaningful to the witness, not to me.

If I’m ever in a Saudi courtroom and they ask me to swear to tell the truth, they’d be wise to offer me a Bible to swear on rather than a Koran (although I hope I’d tell the truth in any event). And if I felt compelled to lie, I certainly would hope that they would offer me the Koran rather than the Bible.

Similarly, if a Muslim is on the stand here, I’d want to offer him a Koran rather than a Bible. I have never witness a religious conversion on the witness stand, I a really don’t expect to.

Put aside the whole ACLU issue for a moment: What are we trying to accomplish by having people to swear to things that are meaningless to them?

God Bless America, God Save The Republic.