Most everyone has heard the words of Jesus "Swear not at all." But we do not seem to believe they were for us. Why? Where can we prove that Jesus told the people a falsehood? Do we think the Bible is contradictory when it says, "Thou shalt swear by his name"? This seems to be the usual thought - that the Bible is full of contradictions - and so we just take what pleases us and follow what the people in the world customarily do. Because it is custom to swear, we swear, when actually the law of the United States permits us to affirm or deny a statement-that is, say yes or no-without raising the hand to swear. The teaching of Jesus and of the true early church was not to swear under any circumstances. James 5:12 reads: "But above all things, my brethren. swear not. . . but let your yes be yes; and your no be no; lest ye fall into condemnation." Read also Jesus' instruction in Mt. 5:33-37 and 21:16-22. Here Jesus warns against swearing because we can not perform the oath, and we would be taking the name of God in vain! Not only is it wrong to lie deliberately under oath (Leviticus 6:3 and 19:12), but we as 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's sin! But if we merely say yes or no to the best of our understanding, then we are not guilty of using God's name in vain. Also, taking a vow, as in marriage, is another matter. It is merely a "yes" or "no" to God and we are held accountable to keep our word to Him. If we break the vow we have lied to God. But it would not be sin if we take it, neither would it be taking the name of God in vain.
Knowing these truths, how can we account for God's command in ancient Israel to take the name of God in an oath (Deut. 10:20; 6:13; Ex. 22:11)? And why did the patriarchs, David and the men of old swear? See Genesis 21:31 and 11:42 and 53 for the patriarchs; I Samuel 20:3 for David and numerous other passages showing it was the common practice in those days. Above all, how can we account for the fact that God swears by Himself, when Jesus told us not to swear? (Hebrews 6:13-17; Psalm 110:4; Luke 1:73 about the oath to Abraham). In Isaiah 45:23, God has sworn that every knee shall yet bow to Him. Christians, who now are not allowed to swear, shall do so after being born again into the Kingdom of God that will rule Israel and all the nations! (Isaiah 65:16 and Jer. 4:2) Are these contradictions? Does God change His ways though He denies doing so? Never! God has one and only one way by which he conducts Himself. How can we reconcile the matter? Very easily. The principle of taking God's name in an oath is correct and right. But we must not do it today, because we are subject to error and would be taking it in vain. When we are made on the plane of God, we shall swear by God because we shall he God and cannot lie or swear falsely. And being in the family of God we shall have the power of performing our oaths. This we can't do now. Jesus in the flesh did not swear, to set us an example. But He swore to the fathers before being born of Mary, just as we shall swear later. So we see that the principle of swearing is not wrong; but God commands us not to now in His love to protect us from using His name in vain and bringing sin on ourselves. God permitted the men of old to swear because He gave them the law only in the letter and according to the letter it is right to swear. The purpose for doing so was to teach Israel in the flesh that their righteousness (Deut. 6:24-25) could not fulfill the law. God gave man and has continued to give man the opportunity to prove by hard experience that he can not keep the law and be free from sin in an oath. Furthermore, the patriarchs and men of old were not told, and hence could not know, that, for a man to swear led to sin. It remained for Christ to make the law honorable and magnify it (Isa. 42:21). But people are held accountable according to the knowledge possessed. We know from the words of Jesus it is wrong to swear. And we have the Spirit to obey the law in the spirit of its meaning. Those men of old had not the Spirit as we do (John 7:39; Deut. 5:29). God did not require of them what they did not know.