Q. 1. What is the Second Commandment and what sin does it condemn?
A. 1. The Second Commandment is, "You shall not take the Name of the Lord your God in vain.”
What is forbidden by this Commandment? It is forbidden to use the Name of God in any profane or irreverent way, as by cursing and blasphemy.
Among all the words of Revelation, there is one which is unique: the revealed name of God. God confides his name to those who believe in him; he reveals himself to them in his personal mystery. The gift of a name belongs to the order of trust and intimacy. "The Lord's name is holy." For this reason man must not abuse it. He must keep it in mind in silent, loving adoration. He will not introduce it into his own speech except to bless, praise, and glorify it. [Cf. Zech 2:13; Ps 29:2; 96:2; 113:1-2] (C.C.C. # 2143)
The second commandment forbids the abuse of God's name, i.e., every improper use of the names of God, Jesus Christ, but also of the Virgin Mary and all the saints. (C.C.C. # 2146)
What is an oath? An oath is a calling upon God to witness the truth of what we say. “The second commandment forbids false oaths. “Taking an oath or swearing is to take God as witness to what one affirms. It is to invoke the divine truthfulness as a pledge of one's own truthfulness. An oath engages the Lord's name. ‘You shall fear the LORD your God; you shall serve him, and swear by his name.’ [Deut 6:13]”(C.C.C. # 2150)
Example: When a person places his hand on the Holy Bible in a courtroom and testifies to tell the truth, he is making an oath.
What is perjury: Perjury is a false oath; calling upon God to witness the truth of something we know to be false. A person commits perjury when he makes a promise under oath with no intention of keeping it, or when after promising on oath he does not keep it. Perjury is a grave lack of respect for the Lord of all speech. Pledging oneself by oath to commit an evil deed is contrary to the holiness of the divine name.” (.C.C.C. # 2152)
What is a vow? A vow is a solemn promise made in the Name of God to do something pleasing to Him. What are the things usually promised in a vow? Men and women who enter religious communities usually promise in the form of a vow to live in Chastity, Poverty, and Obedience. Note: A lay-person, living in the world, should not make a vow of any kind except after careful consideration and with the advice of an experienced priest.