In the sermon on the mount, Jesus commands us not to swear at all and, “Simply let your ‘Yes’ be ‘Yes,’ and your ‘No,’ ‘No’; anything beyond this comes from the evil one.” (Matthew 5:37; NIV). So is it ok for a Christian to make vows at a wedding and to swear to tell the truth in court with their hand over the Bible? If so, why? Thanks in advance!
This is a debatable area. I believe what we need to do is to understand the context of Judaism in the 1st century to really know what Jesus was addressing. This is the hermeneutics of the passage. In order to understand the context, we must recognize that the Jews had a habit of swearing by the temple or by the items in the temple or by the shekinah/presence of God in the temple and all other sorts of things that they swore by. It was an adult version of what kids do when they say “cross my heart, hope to die, stick a needle in my eye.” Some would say that Jesus is condemning every single form of swearing or taking oath of any sort. I personally believe this is over the top and is taking what Jesus is commanding out of context. Jehovah Witness refuse to pledge allegiance and refuse to join the military at least in part because of their misinterpretation of Matthew 5:37. A famous historical example is that Robert Boyle refused the presidency of the Royal Society back in the 17th century because, for religious reasons, he believed it was a Christian obligation to not take an oath.
What I believe Jesus means in Matthew 5:37 is that we should avoid all kinds of superstitious things such as swearing by a particular item in the temple, as if this would be an even stronger oath than if we simply said “I will.” To do so makes Christianity appear to be foolish. We should do what Jesus said here and let our yes simply be yes. For example, at a wedding it is sufficient to say “Yes, I will.” It is unnecessary for a Christian to say at a wedding “I will, so help me God” or “By God I will.” I am not sure it would be sinful to do this, as long as we do not break the spirit of what Jesus said here. As to taking an oath as required by a government agency, this is a grey area. Personally, it would not bother me to “swear” to tell the truth in a court of law because in my heart I know that I am simply saying that I will tell the truth, but I am doing it in a form required by the government. Arguably, raising our right hand or placing our hand on a Bible is another example that could be labeled as superstitious and therefore outlawed by Jesus. Others might find this offensive to do. Fine. In this case, they might refuse to take such an oath based on conscience. However, in my opinion, to do so, not in order to really prove that you really, really, really, honestly mean it (I assume you get my drift there), but simply because a government is asking us to use that form, I do not see this as violating the spirit of what Jesus is commanding.
To summarize, in a public or a private Christian setting we should simply say something like “I will,” or “yes.” But in a cultural setting, within reason, we can take an “oath” as long as we know in our hearts and minds that we are simply saying “yes, I will,” but doing so in a way customary to our culture. However, I definitely would not swear in the name of Buddha or of Father Sky or Krishna.
I hope this helps.