

It’s a social more, nothing more ;)
In other words, it doesn’t matter what you swear by, it’s the open swearing that matters in terms of legality. See, the oath is what makes perjury prosecution “acceptable”. When a witness is sworn in, the process isn’t so much about them actually promising to tell the truth as it is a warning to them that truth is expected and will be enforced.
Yeah, historically, there’s more to it than that, but it boils down to everyone involved knowing that truth is expected, and lying comes with consequences (well, if you get caught at it, and can’t avoid those consequences in some way. The system ain’t perfect at its best, and is rarely at its best).
Swearing on a bible is just tradition based on centuries of christians and christianity being in power. You can opt to “affirm” instead, giving an non religious oath that is just a binding.
But, in any real terms, an oath isn’t necessary to begin with. When the system/state/government/people have the power to punish you for lying, they don’t even really have to notify you that lying will come with consequences. Doing so is a nicety that at least prevents anyone from being able to say they didn’t know they couldn’t lie. Not that trying it in the absence of an oath would be worth spit, but it saves time.
But having an expectation of truth under duress is a cultural thing. And it can be a form of duress. You can be compelled to appear and give testimony, with consequences got refusing. In other situations, being under duress can be a defense against a charge, though the standard for what degree of threat serves to meet that criteria is pretty steep. But it’s an understood thing that you aren’t supposed to lie during legal proceedings. It doesn’t have to be that way, but it certainly does make it easier to have a degree of conformity to the truth among people that might otherwise lie.










I’ve got something long and hard for stars.
It’s a telescope.