The phrase "swear on Bible" is a common expression used to suggest that someone is being completely truthful. However, sometimes the truth can be difficult to swallow, and there may be situations where a person would want to do the opposite of swearing on the Bible. In such cases, they may use antonyms to convey their message. Some antonyms for the phrase "swear on Bible" include lying, deceiving, or perjuring oneself. These words suggest that the person making the statement is not being truthful, and they may be deliberately misleading others. While swearing on the Bible is considered a solemn promise, its antonyms indicate a disregard for truth and honesty.