In Matthew 5:33-37 Jesus referred to a series of laws in the Old Testament relating to the theme of not swearing falsely. Making an oath and not fulfilling it is wrong. Jesus encouraged his disciples not to swear such oaths, but to just say yes or no. An oath does not guarantee fulfillment of an obligation. Oaths are a form of leverage by the oath taker supposedly making that person more believable. In actuality, they underline the fact that we humans are too often unreliable and untruthful. Swearing by things is a delusion and guarantees nothing. By invoking heaven or earth, we are in effect deluded that a veneer of honesty can change liars into truth-tellers. In the church, we do not need to engage in such useless exercises. We simply need to be truthful as best as we can.
Jesus taught that it was better not to swear any oaths at all than make one and not fulfill it. Did that include pledges of allegiance, wedding vows or oaths in court? God swore an oath (Hebrews 6:16-18), Jesus answered under oath (Matthew 26:63-64), and Paul wrote oaths in his letters (2 Corinthians 1:23; Galatians 1:20). What did Jesus not say? He did not say “swear not at all” period, but immediately included a list of qualifiers under which swearing an oath had led to vows being taken too lightly. Oaths were allowed in the Old Testament, but when anything less than God was sworn by, people were no longer taking their vows seriously. Jesus did not condemn the swearing of sincere oaths, but frivolous and deceptive ones. Christians ought not make oaths that cover up perjury or insincerity but simply answer yes or no.
In a world with false and deceptive advertising, lying politicians on both sides, banks which charge the poor more than the rich, and a general distrust of government and industry surely there is an urgent need for truth-telling.