Should Christians swear by an oath?
The teaching of Jesus and of the early inspired true New Testament Church was not to swear under any circumstances. The Scriptures are very plain on this point: "But above all things, my brethren, SWEAR NOT... but let your yea be yea; an your nay, nay; lest ye fall into condemnation" (Jas. 5:12).
Jesus Himself personally instructed: "...I say unto you, 'Swear not at all; neither by the heaven; for it is God's throne: Nor by the earth; for it is his footstool: neither by Jerusalem; for it is the city of the great King. Neither shalt thou swear by thy head because thou canst not make one hair white or black. But let your communication be, Yea, yea; Nay, nay: for whatsoever is more than these cometh of evil (the evil one, or of sin)'" (Matt. 5:33-37).
Here Jesus warns against swearing because we cannot perform the oath and we would be taking the name of God in vain.
Not only is it wrong to lie under oath, but we as mortal human beings are so prone to mistaken judgment or lack of knowledge that any error we would make under oath would be to take the name of God in vain. It is sin!
We are merely to say, "Yes," or "No," to the best of our understanding. Then we are not guilty of using God's name in vain. It is the law of the United States to permit affirmation — that is, say "Yes" or "No" — without raising the hand to swear.
If men are not to swear by an oath, how are we to account for the fact that God swears by Himself? (Heb. 6:13-17; Ps. 110:4; Luke 1:73.) In Isaiah 45:23, God has sworn that every knee shall yet bow to Him.
The answer is simple. The right to take an oath belongs to God. God alone has infallible judgment. When we are made immortal members of the God family, prophecy proves that we shall swear by God because we shall be God — members of the God family. Then we shall have the power to perform our oaths. This we cannot do now.
Jesus, while in the flesh, did not swear, setting us an example (I Pet. 2:21). Men in Old Testament times did swear, but it was not revealed to them that God alone can properly exercise such a right.
The word of a Christian is to be good. One GREAT characteristic of God is the infallibility, the ABSOLUTE surety of His Word! Our word — our simple "Yes," or "No," is to be worth far more than thousands of oaths, sworn by this or that! Paul did call upon God as his witness! Paul said: "... before God, I LIE NOT!" (Gal. 1:20). He affirmed that he was telling the TRUTH, but he did not swear "by" anything.
People are held accountable according to the knowledge possessed. We now know from the very words of Jesus that it is wrong for mortal men to swear by an oath at any time. Taking an oath is a Divine prerogative.