As partaker of Christ's anointing, and in the office of believer, the child of God speaks on three different levels. In general conversation he is called to speak the truth in love, avoiding all lying as the proper work of the Devil. At certain times he makes vows: confession of faith, marriage, baptism, and installation into church office. When we speak a vow unto the Lord we must not defer to pay it (Eccl. 5:4). Occasionally, the child of God is required to sware an oath. The Catechism, in Lord's Day 37, instructs us that we may swear religiously by the name of God  "when the magistrates demand it of the subjects; or when necessity requires us thereby to confirm fidelity and truth to the glory of God and the safety of the neighbor." A lawful oath is one sworn in the name of God who alone knows the heart, understands the truth of every matter, and both can and will punish those who swear falsely.

Scripture warns us against swearing in the name of a false god or by any creature (Jer. 12:16), despising an oath (Ex. 16:59), loving a false oath (Zech. 8:17), swearing carelessly (Matt. 14:9), or using an oath among brethren (Matt. 5:34ff., James 5:12). So serious is an oath that it binds the soul (Num. 30:2), must be kept even when it leads to our own hurt (Ps. 15:4), and if broken involves one in sin which must be confessed (Lev. 5:4). When men swear an oath they swear by the greater, and such an oath is to them an end of all striving and disputation; they simply place the matter in the hands of God for His righteous disposition. When God makes promises He swears by Himself because He can swear by no greater ( Heb. 6: l3ff.). In the Old Testament we read over forty times that God swore an oath to the fathers concerning His covenant and the land that He would give them for an everlasting possession. Once we read that God swore in His wrath that the people of Israel would not enter into His rest (Heb. 3:11). In that God swore by Himself many times, we understand the oath to be His institution and to be legitimate in certain circumstances.

The priests who served under the old covenant were made priests without an oath, but God made Christ a Priest with an oath, when He said unto Him, "The Lord hath sworn and will not repent, thou art a priest forever after the order of Meichizedec" (Ps. 110:4; Heb. 7:21). This makes Christ a better Priest of a better covenant. Although this oath, recorded in the Scriptures, is for our instruction and assurance, it also had great significance for Christ to whom it was spoken. During the difficult years of His ministry, and especially when He was betrayed, denied, rejected, and forsaken, our great High Priest could recall the eternal oath of God. He found consolation for His weary soul, and strength for the final descent into hellish agonies.

But the oath of God is also our strong consolation. God wills that His people live a robust, vibrant life of faith, that they stand upon His promises, that they lay hold of the hope that is set before them, and that they flee for refuge in Christ. Accordingly, God has given us two precious things in which it was impossible for Him to lie: His immutable counsel with Christ and His church at its very heart, and the confirmation of that counsel with an oath. Receiving these two things, counsel and oath, we have a strong consolation! Let the oath of God, then, be the end of all strife, doubt, and disputation that can go on between the old and the new man in us; let consideration of God's oath upon His promise still our fears and give us the answer of a good conscience toward God.

As we live together in the church, "let our yea be yea, and our nay nay, for whatsoever is more than these cometh of evil" (Matt. 5:37). Let us honor one another as saints in whom the Holy Spirit works a love for all truth as well as for the brotherhood. And when it is required of us to swear an oath, let us do that boldly in the name of our God, who has instituted it for the glory of His name, the welfare of His church, and the good order of society.