"Thou shalt not take the name of the Lord thy God in vain: for the Lord will not hold him guiltless that taketh his name in vain."

The duties required in the third commandment requires that the name of God, his titles, attributes, ordinances, the word, sacraments, prayer, oaths, vows, lots, His works, and whatsoever else there is whereby He makes himself known, be holy and reverently used in thought, meditation, word, and writing; by an holy profession, and answerable conversation, to the glory of God, and the good of ourselves and others. (taken from the Larger Catechism of the Presbyterian Church - Answer to Question 112)

The sins forbidden in the third commandant are, the not using of God's name as is required; and the abuse of it in an ignorant, vain, irreverent, profane, superstitious, or wicked mentioning or otherwise using His titles, attributes, ordinances, or works, by blasphemy, perjury;...murmuring and quarreling at, curious prying into, and misapplying of God's decrees and providences; misinterpreting, misapplying, or any way perverting the Word, or any part of it, to profane jests, curious and unprofitable questions, vain janglings, or the maintaining of false doctrines;...or any wise opposing of God's truth, grace and ways; making profession of religion in hypocrisy, or for sinister ends; being ashamed of it, or a shame to it, by uncomfortable, unwise, unfruitful and offensive walking, or backsliding from it. (taken from the Larger Catechism of the Presbyterian Church - Answer to Question 113)

Forbidden:  Dishonoring of and demotion of His name in speech, thought, or act.