Answer. No; for a lawful oath is a calling upon God, as the one who knows the heart, that he will bear witness to the truth, and punish me if I swear falsely; which honor is due to no creature.
Exposition
In these two Questions the doctrine respecting the oath is explained at large.
The Doctrine of the Oath
Concerning this we must enquire,
I. What is an oath?
II. By whom are we to swear?
III. Is it lawful for Christians to make oath?
IV. What are the things concerning which we are to make oath?
V. Are all oaths to be kept?
I. What Is an Oath?
An oath is often used in the Scriptures for the whole worship of God, as, “Thou shalt swear by his name.” “In that day shall five cities in the land of Egypt speak the language of Canaan, and swear to the Lord of hosts.” “Every knee shall bow unto me, every tongue shall swear.” (Deut. 10:20. Is. 19:18; 45:23.) Concerning the worship of the New Testament it is said: “He who blesseth himself in the earth, shall bless himself in the God of truth, and he that sweareth in the earth, shall swear by the God of truth.” “If they will diligently learn the ways of my people, to swear by my name, then shall they be built in the midst of my people.” (Is. 65:16. Jer. 12:16. The reason of this is that we profess him as our God, by whom we swear. An oath, properly speaking, is a calling upon God, as the one who knows the heart, that he will bear witness to the truth, and punish me if I swear falsely. It is in this way that the Catechism defines a lawful oath, which definition is taken from the form of swearing which the apostle Paul uses, when he says, “I call God for a witness upon my soul, that to spare you I came not as yet unto Corinth.” (2 Cor. 1:23.)
It is said in the definition just given, that God will bear witness; viz., by preserving and doing good to him that swears, if he swear religiously, and by punishing and destroying him if he swear falsely. For the oath was instituted by God, that it might serve as a bond of truth between men, and be a testimony that God is the author and defender of truth.
II. By Whom Are We to Swear?
We must swear by the name of the true God alone; 1. Because God has commanded that we swear by him alone, as he alone is to be feared and worshipped. “Thou shalt fear the Lord thy God, him shalt thou serve, and to him shalt thou cleave, and shalt swear by his name.” (Deut. 10:20.) 2. God positively forbids us to swear by any other name. “Make no mention of the names of other gods.” (Ex. 23:13.) 3. God wills that the worship of invocation be given to him alone, and condemns those who in their oaths join creatures with himself. The oath now, according to the definition, is one of the ways in which we call upon God, being comprehended in it. 4. An oath ascribes to him by whom it is taken, a knowledge of hearts, omniscience, omnipresence, &c. And it is indeed necessary that he by whom we swear should be possessed of infinite wisdom, and have a knowledge of the heart; because when oaths are taken it is not concerning things which are manifest, and of which there is no doubt, but of things unknown and uncertain, and of which he only, who has a knowledge of all hearts, can judge whether men speak the truth, or that which is false. But God alone knows the heart, is omniscient and every where present. And as Christ and the Holy Ghost are God, and know all things, as the following passages of Scripture sufficiently testify, we are also to swear by them. “He knew all men, and needed not that any should testify of man, for he know what was in man.” “The Spirit searcheth all things.” (John 2:24, 25. 1 Cor. 2:11.) 5. We commit the execution of punishment to him by whom we swear, and also attribute such power to him as is necessary to maintain the truth, and punish those who are guilty of perjury. But God alone is possessed of such power, and inflicts punishment upon the wicked. “Fear not them which kill the body, but are not able to kill the soul; but rather fear him which is able to destroy both soul and body in hell.” (Matt. 10:28.) Men cannot be the avengers of those who are guilty of perjury, inasmuch as those who swear falsely may escape the judgment of men, either because they do not know the heart, so as to see whether those who swear are practising a deception or not, or because those who perjure themselves are too powerful to be punished by men. It follows, therefore, that we must not take an oath except by the name of God alone.
It is apparent, from what has now been said, that oaths which are taken by the saints and other creatures are idolatrous, and prohibited by God.
Obj. But Joseph swore by the life of Pharaoh. (Gen. 42:15.) Therefore it is lawful to swear by men and creatures. Ans. There are some who admit that Joseph sinned in following the custom of the Gentiles, who were wont to swear by things, that his brethren might not by this means recognise him. But we may give a different reply to the objection, by maintaining that his language does not, properly, contain an oath, but merely a strong affirmation; so that the sense is, As truly as Pharaoh lives, or is in safety; or, As truly as I desire him to be in safety, so truly do I affirm these things. The same interpretation must be given to all other asseverations of a similar character, instances of which may be found in 1 Sam. 1:27; 15:55; 20:3; 25:26. These forms of speech are not properly oaths, but strong declarations, made for the sake of placing something in the clearest light by comparing it with something known and manifest; so that we are to understand them as meaning that those things which are affirmed are as certain, as that he liveth, who is named by the person making the declaration.