348 Q. When may we take an oath?  A. We may take an oath when it is ordered by lawful authority or required for God’s honor or for our own or our neighbor’s good.

An oath is generally taken in a court of law when the judge wishes to find out the truth of the case.  We may be a witness against one who is guilty, or in defense of an innocent person, and in such cases a lie would have most evil consequences.  The judge has a right, therefore, to make us take an oath that we will testify truly.  Officers of the law, magistrates, judges, etc., take an oath when entering upon their duties that they will perform them faithfully.

349 Q. What is necessary to make an oath lawful?  A. To make an oath lawful it is necessary that what we swear be true, and that there be a sufficient cause for taking an oath.

350 Q. What is a vow?  A. A vow is a deliberate promise made to God to do something that is pleasing to Him.

“Deliberate”—­that is, with full consent and freedom.  If we are forced to make it, it is not valid.  “To God,” not to another; though we may vow to God that we will do something in honor of the Blessed Virgin, or of the saints, or for another.  “Something pleasing,” because if we promise something that is forbidden by God or displeasing to Him, it is not a vow.  A solemn promise, for instance, to kill your neighbor or steal his goods could not be a vow.  You would commit a sin by making such a vow, and another by keeping it, for if you promise something you cannot do without committing sin then you must not keep that promise.  We have an example in the life of St. John the Baptist.  King Herod was leading a sinful life, and St. John rebuked him for it.  The wife of the king’s brother—­Herodias was her name—­hated St. John for this, and she sought to have him killed.  Once when the king had a great feast and all his notables were assembled, this woman’s daughter danced before them, and the king was so pleased with her that he vowed to give her whatever she asked.  He should have said, if it is something pleasing to God, but he did not.  Her mother made her ask for the head of John the Baptist.  The king was sad, but because he had made the vow or promise he thought he had to keep it, and ordered St. John to be beheaded and his head brought to her. (Matt. 14).  He was not bound to keep any such vow, and sinned by doing so.

Again, they also commit sin who become members of such secret societies as the freemasons or similar organizations, promising to do whatever they are ordered without knowing what may be ordered; for they sin not only by obeying sinful commands, but by the very fact of being in a society in which they are exposed to the danger of being forced to sin.  Such secret societies are forbidden by the Church because they strive to undermine its authority, and make their rules superior to its teaching.  They also influence those in authority to persecute the Church and its ministers, and do not hesitate to recommend even assassination at times for the accomplishment of their ends.  Therefore the Church forbids Catholics to join societies of which (1) the objects are unlawful, (2) where the means used are sinful, or (3) where the rights of our conscience and liberty are violated by rash or dangerous oaths.