A swearing that asserts the truth of a statement or promise, typically in the name of God. An oath is often made formally and solemnly. For example, a witness at a trial may swear that his or her testimony will be the full truth. Similarly, one who takes an oath of office swears to fulfill the duties and responsibilities of the office. The taking of oaths was criticized by Jesus, who urged in the Sermon on the Mount, "Do not swear at all," not by heaven or the earth or Jerusalem or by one's own head (Mt 5:33-37). This teaching is repeated in Jas 5:12. Since early Christian times, some have interpreted this teaching literally and refused to take oaths. A rigorist refusal to swear oaths was the predominant Christian attitude in the early centuries of the church. This position against oaths has been continued in modern times by Christian groups such as the Mennonites and Quakers. In many courts today, those with scruples against taking an oath are allowed to affirm (without swearing) that they will tell the truth.
Others have understood the teaching against swearing to criticize the excessive or casual taking of oaths that was common when Jesus lived. Certainly, a Christian should speak the truth at all times, whether or not an oath is involved. A Christian's word should not require an oath to be believed. An oath should be a superfluous addition to a Christian's word. However, since the early centuries of the church, some Christians have allowed the taking of oaths in certain circumstances. Paul calls on God as his witness in several contexts (2 Cor 1:23, Gal 1:20, Phil 1:8). Augustine would allow a Christian to take an oath for a reason of great necessity, if the oath was in the interest of a great good. Article XXXIX of the Articles of Religion states that "vain and rash Swearing is forbidden Christian men by our Lord Jesus Christ, and James his Apostle," but Christian religion does not prohibit one to swear "when the Magistrate requireth, in a cause of faith and charity, so it be done according to the Prophet's teaching in justice, judgment, and truth" (BCP, p. 876).