I recently had the dubious pleasure of writing an affidavit, which is a tedious back-and-forth process involving many drafts and revision. When it was all finalised, my solicitor asked whether I’d like to swear an oath on a Bible or make an affirmation. Being a pragmatic kind of guy, I asked what the legal difference is, to which she asked, “Well, are you religious?” Not wavering from my tack, I refused to answer if it wasn’t going to make a difference legally.
The implication is, of course, that a “religious” person might prefer to swear an oath on a Bible. But let’s see what Jesus had to say about oaths. Take Matthew 5:34-37, for example (NIV):
But I tell you, do not swear at all: either by heaven, for it is God’s throne; or by the earth, for it is his footstool; or by Jerusalem, for it is the city of the Great King. And do not swear by your head, for you cannot make even one hair white or black. Simply let your “Yes” be “Yes”, and your “No”, “No”; anything beyond this comes from the evil one.
The Epistle of James contains a similar exhortation (5:12 NIV):
Above all, my brothers, do not swear — not by heaven or by earth or by anything else. Let your “Yes” be yes, and your “No”, no, or you will be condemned.
Both of those verses strongly support making an affirmation as far as I can see. This would seem to make the option of swearing an oath on a Bible redundant.