One of the Ten Commandments is “Thou shalt not take the name of the Lord in vain. For the Lord will not hold him guiltless for taking his name in vain.” Among other meanings, it meant: You shall not make wrongful use of the name of the Lord your God." People have taken this to be an injunction against using God’s name to curse someone and also even to speak God’s name. Notice again, God is portrayed as a male and a punishing male if you don’t obey him.
They also have taken it to mean that you better not use God’s name in an oath, either, as in “I swear to God!” Some Catholic priests taught that if a promise was made in the name God, and that promise was broken, God would punish those who took His name in vain.
The Calvinists believed that an oath is calling God to witness that what we say is true. An oath is a form of worship of God as a profession of faith. When human testimony fails, people call on the name of God as witness. He is the only one able to bring out what is hidden and know what is in our hearts. False swearing robs God of his truth, and therefore it is a serious matter. They warn us that just because people have become used to indiscriminate public swearing it doesn’t mean they won’t be punished for it.
This fear of punishment abides to this day. People know somehow that it is wrong to curse and swear. It is offensive to others and shows a certain amount of insecurity, paucity of vocabulary, and lack of thought. But apart from that there is a primitive fear of punishment that we are invoking a power, higher than ourselves, for our petty aims.