Hebrews 6:18Meaning & Commentary from the Church Fathers

“That by two immutable things, in which it is impossible for God to lie.” What two? Which things? By what He said and promised, and by the fact that He joined an oath to the promise. Since among men what is confirmed by an oath is considered more trustworthy, He therefore added an oath. Do you see that God does not look to His own dignity? In order to persuade men, He permits even what is unworthy of Him to be said of Himself, precisely so as to give assurance. Concerning Abraham, the Apostle shows that everything was God’s work and not the work of Abraham’s longsuffering, since God was pleased to add an oath. Just as men swear, God also swore by Himself. Men swear by Him as greater, while He did not swear by one greater, and yet He fulfilled it.

“That by two immutable things, in which it is impossible for God to lie.” Which two? Both by the fact that He simply spoke and promised, and by the fact that He joined an oath to the promise. Since among men what is confirmed by an oath is considered more trustworthy, God also added it. “In which” means “from which”: from these two things the promise appears most certain, and it is impossible for God to lie. Therefore, as He swore for our sake, though it is unworthy of Him to swear, so also understand the phrase that “He learned from the things which He suffered.” For men too consider what is known by experience more trustworthy. “We who have fled for refuge might have strong consolation, to lay hold (κρατήσοα) of the hope set before us.” That is, great consolation and encouragement.

The Lord, through Moses, gave ordinances concerning sacrifices, and the whole book called Leviticus is full of prescriptions about them. Thus the one who offered sacrifice might receive approval, while the one who neglected them, as disobedient to the command, would incur blame. Yet through the prophets He says, “Who has required this from your hands? I did not speak to your fathers about sacrifices of slaughter, nor did I give them commandments concerning burnt offerings” (Isa 1:11-13; cf. Jer 7:22). From this it may appear that Holy Scripture is not in agreement with itself, or that God, Who gave these commandments, is not true. But the Author of truth is not false, for “it is impossible for God to lie,” as Paul affirms.

Through two immutable things, in which it is impossible for God to lie: one, that He swore by Himself; and another, of which David said, The Lord has sworn and will not repent, You are a priest forever according to the order of Melchizedek. To us, who have become heirs of this promise, firm consolation appears. We have fled for our strengthening not to the justice of God, that is, not like those of old, but have turned to the very mercy of God.

By two things the Apostle meant the word and the oath. For even by using only His word, God fulfills the promise. Much more does He do so when He joins an oath to the word. This, says the Apostle, He did to give us firm assurance. He teaches us to await the promises of God and not to fall into unbelief if we do not see the promised thing fulfilled. For hope that is seen is not hope (Rom 8:24).

It is the same either way. If God simply gave a promise, it is immutable and firm. If an oath is added to the promise, it remains equally immutable and firm. The oath was added for our more perfect assurance, so that on these two grounds we might have strong consolation and lay hold of the hope set before us. That is, we should have the strongest attraction of soul and persuasion of mind toward inheriting what was promised. We have fled to God, certainly by faith, as did Abraham, our father according to faith.

The two immutable things are God’s promise and His oath. By these two it is impossible for God to lie. The hope set before us is the hope of receiving in Christ Jesus the blessing that grants the Kingdom of heaven. God promised this blessing to Abraham with an oath, saying, “Blessing I will bless you,” and, “In your seed all the nations of the earth shall be blessed” (Gen 22:17-18). God made an oath so that, by these two unchanging and immutable things, namely the promise and the oath, we might flee by faith to Jesus Christ. We should be strongly persuaded to undoubting hope that we will receive blessing and salvation. Since God promised with an oath, we should be assured that it is impossible for Him not to fulfill the promise. Thus we should remain unshaken in this hope amid all circumstances that meet us during our temporal life.

By two immutable things, in which it is impossible for God to lie. Immutability refers to the promise and the oath. The Apostle applies them to Christians and wishes to give them consolation in this. He says that, in giving promises to Abraham, God gave promises also to us in his person, as Abraham's true descendants by faith (Rom 4:12). And by promising Jesus Christ the high priesthood with an oath, God thereby assures us of the eternal salvation that we receive through this priesthood (Heb 7:19-20).

In this section of chapter 6, the Apostle urges his readers to await the fulfillment of the divine promises with faith and longsuffering. As an example of constancy in hope, he sets forth Abraham, who "after he had patiently endured, obtained the promise" (v. 15).

He places the foundation of firm hope in the fact that God confirmed His promises by an oath, and that He cannot lie either in oath or in promise (v. 18). At the same time, the Apostle gives us the true understanding of an oath and of its lawful use.

“For men swear by the greater, and an oath for confirmation is the end of every dispute among them” (Heb 6:16). But do men do well when they swear, and is an oath at all permissible? No, it is not permissible, some speculators answer; an oath is a sinful thing, as the Quakers, Count L. Tolstoy, and others say. But these speculations are refuted by the Apostle’s following words concerning God. Desiring to show more abundantly to the heirs of the promise the immutability of His will (Heb 6:17), for example, to Abraham, that he would become father of many nations, God interposed an oath. Since He could swear by no one higher, He swore by Himself, as said above (Heb 6:13).

To move his readers still more toward longsuffering, the Apostle next shows that, as heirs of the promises given to Abraham, they must pay special attention to this: God swore to Abraham concerning the faithful fulfillment of these promises. And what is an oath? An oath has great significance. It puts an end to every contradiction and every dispute, finally confirming the truth of the words of the one who swears. On this basis God also, for the reassurance of all whom the promise concerned, swore according to human custom that He would fulfill it. Thus two things should reassure us: the promise itself, which as the word of the true God is already immutable in itself, and still more, the oath of God.