The interpretation timeline
Hebrews 6:18 Douay-Rheims

That by two immutable things, in which it is impossible for God to lie, we may have the strongest comfort, who have fled for refuge to hold fast the hope set before us.

A.D. 99 – 1871 8 witnesses

Patristic

before A.D. 750
99
A.D.
Clement of Rome Patristic
d. A.D. 99
“With this hope, then, let us attach ourselves to the one who is faithful to promises and just in judgments. The one who bids us to refrain from lying is all the less likely to lie. For nothing is impossible to God, save lying.”
373
A.D.
c. A.D. 296–373
“Through Moses God gave commandments about sacrifices, and the whole book of Leviticus is taken up with acceptable ways for them to be carried out. The Lord, through the prophets, found fault with those who contemptuously misstated these things, calling them disobedient to the commandment. He told them, "I have not asked you to do these things!… Neither did I speak to your fathers about sacrifices, nor give them commands about whole burnt offerings."Some have put forth the opinion that either the Scriptures do not agree or that God, who gave the commandment, is a liar. But in this there can be no disagreement—far from it. The Father, who is truth, cannot lie, "for it is impossible for God to lie," as Paul affirms. Actually, these things are plain to those who accept the writings of the law with faith and look at them in the right way. Here is my explanation, and may God grant by your prayers that I am not too far from the truth. It does not appear to me that God gave the commandments and the law concerning sacrifices right away when he led them out of Egypt. Nor did he who gave the law really pay any attention to the whole burnt offerings, as such. He was looking ahead to those things that were prefigured and pointed out by them. "For the law has but a shadow of the good things to come." And "Those regulations were set forth until the time of reformation."9 That is why the whole law did not deal with sacrifices, although it did include commands concerning them. By means of these commands it began to teach people, calling them away from idols and drawing them to God, giving them proper teaching for the times in which they lived. So you see, God did not give the people those commands about sacrifices and offerings when he brought them out of Egypt, nor even when they first came to Mount Sinai. God is not like people, that he should want those things for himself. No, he gave the commandment so that they might know him and his Word (the Son)—and forget about those so-called gods that do not really exist but appear to do so because of the show people put on.”
Source
407
A.D.
John Chrysostom Patristic
A.D. 347–407
“"That by two immutable things, in which it was impossible that God should lie." What are these two? The speaking and promising; and the adding an oath to the promise. For since among men that which is confirmed by an oath is thought more worthy of credit, on this account He added that also. Seest thou that He regardeth not His own dignity, but how He may persuade men, and endures to have unworthy things said concerning Himself. That is He wishes to impart full assurance. And in the case of Abraham indeed the Apostle shows that the whole was of God, not of his patient endurance, since He was even willing to add an oath, for He by whom men swear, by Him also God "sware," that is "by Himself." They indeed as by one greater, but He not as by one greater. And yet He did it. For it is not the same thing for man to swear by himself, as for God. For man has no power over himself. Thou seest then that this is said not more for Abraham than for ourselves: "that we" (he says) "might have strong consolation, who have fled for refuge to lay hold on the hope set before us." Here too again, "after he had patiently endured he obtained the promise." "Now" he means, and he did not say "when He swore." But what the oath is, he showed, by speaking of swearing by a greater. But since the race of men is hard of belief, He condescends to the same things with ourselves. As then for our sake He swears, although it be unworthy of Him that He should not be believed, so also did the Apostle make that other statement "He learned from the things which He suffered," because men think the going through experience more worthy of reliance. What is "the hope set before us"? From these past events (he says) we conjecture the future. For if these came to pass after so long a time, so certainly the others will. So that the things which happened in regard to Abraham give us confidence also concerning the things to come.”
Source

Scholastic

c. 1100 – 1500
1273
A.D.
Thomas Aquinas Catholic
1225–1274
“Above, the Apostle showed the reason why he was confident concerning these things, and this was on account of the good things they had done; here he shows the same thing from the promise made to the fathers. Hence concerning this he does two things. For first he sets forth the promise; second he assigns the reason for what has been said, at the place, "For men." Concerning the first he does three things. For first he shows to whom the promise was made; second he shows that the manner of the promise is fitting, at the place, "since no one," etc.; third, the effect of the promise, at the place, "and so, with long patience." The promise was made to Abraham. Gal. 3:16: "To Abraham were the promises made," et cetera. And the reason for this is that through faith we cling to God, and therefore through faith we obtain the promises. For the first example of faith was in Abraham, and this because he was the first to withdraw from the company of unbelievers. Gen. 12:1: "Go forth from your land," et cetera. Second, because he was the first to believe something that was above nature. Rom. 4:18: "Who against hope believed in hope." Hence Gen. 15:6: "Abraham believed God, and it was reputed to him unto justice." For he was the first to receive the seal of faith, namely circumcision, Rom. 4:11. The manner of the promise concerns two things: first, as to the oath interposed; second, as to the words of the promise, at the place, "unless blessing I shall bless you," et cetera. He says therefore: God, wishing to show his promise firm and stable, because he had no one greater than himself by whom he might swear — Ps. 112:4: "The Lord is high above all nations," etc. — swore by himself. Gen. 22:16: "By myself have I sworn, says the Lord," et cetera. In this you have an example that an oath is not of itself unlawful, because Scripture attributes nothing to God which is in itself a sin. For Scripture intends to order us and lead us to God. Eph. 5:1: "Be imitators of God as children," et cetera. Yet the frequency of swearing is forbidden. Ecclus. 23:9: "Let not your mouth be accustomed to swearing," et cetera. Likewise an oath in vain. Ex. 20:7: "You shall not take the name of your God in vain." Accordingly, when he says, "unless blessing," etc., he shows the manner of the promise; as if to say: let me not be believed, unless I bless you, so that the manner of swearing is, as it were, by execution. Now he says "blessing," which pertains to the conferring of goods. For the blessing of the Lord makes rich, as is said in Prov. 10:22. And "multiplying I shall multiply you," which also pertains to the numerousness of offspring. And both were promised to Abraham, as is clear from Gen. 14 and 25. Now he doubles the word, saying "blessing I shall bless," to designate temporal and spiritual goods, and the continuity of the blessing. Or, "blessing I shall bless" refers to the multitude of holy offspring, which in Gen. 15:5 is designated by the stars of heaven, where it is said, "Look up to heaven, and number the stars, if you can," et cetera. And "multiplying I shall multiply" refers to the numerousness of the evil and perverse offspring, which in the same place, namely chapter 22, is designated by the sand of the sea. The word "multitude" is also doubled, which is on account of the numerousness of the good or evil offspring; or on account of the continuity of the multitude. Or, "I shall bless" refers to the goods of grace, and "I shall multiply" to the goods of glory. Ps. 30:19: "How great is the multitude of your sweetness, O Lord," et cetera. The effect of the promise was that, bearing with long patience, he obtained the promise. Long patience consists not only in doing something great, but also in waiting for a long time. Now Abraham had the promise, and yet he never possessed a foot's pace of ground, as is said in Acts 7:5. And even into old age he did not receive offspring, and yet he did not fall from hope. James 5:10: "Take as an example, my brothers, the prophets of evil outcome, and of long patience, and of labor, and of patience," et cetera. Is. 51:2: "Look unto Abraham your father," et cetera. Then, when he says, "for men swear by one greater than themselves," he sets forth the reason for what has been said, and concerning this he does three things. For first he sets forth human custom; second he assigns the reason for the custom, at the place, "wherein more abundantly"; third he adds the fruit of the reasoning, at the place, "that by two immutable things." Now human custom is set forth as twofold: one as to that by which one swears; the other as to the effect of the oath, at the place, "and of all controversy." Now that by which one swears is something greater, and this reasonably. For to swear is nothing other than to confirm what is doubtful. Therefore, just as in the sciences nothing is confirmed except through that which is more known, so, because nothing is more certain among men than God, it is by him, as by what is greater and more certain, that one swears. But on the contrary: sometimes one swears by the Son, who is lesser, as when it is said, "by Christ." And sometimes by a creature, as Joseph swore by the health of Pharaoh, Gen. 42:15. I answer. It must be said that there is a twofold manner of swearing by God: in one way, by simple attestation, as when it is said absolutely, "By God it is so," as if to say: God is my witness that it is so, as I say. Rom. 1:9: "God is my witness, whom I serve in my spirit." And sometimes by execration, which happens when something is bound over to the vengeance of God, if it be not so — for instance one's head, or soul, or something of this kind — as the Apostle swore. 2 Cor. 1:23: "I call God to witness upon my soul," as if to say: I bind over my soul for this testimony, for which I take up the very name of God. And this is most weighty. Now one swears by a creature not insofar as it is such a creature, but insofar as some token of divine power shines forth in it. For since all power is from God, Rom. 13:1, insofar as someone exercises power over some multitude: if one swears by him, one swears by God, whose power shines forth in him. And thus Joseph swore by the health of Pharaoh. This, then, is what he means when he says, "Men swear by one greater than themselves." Now it must be known that those who have already perjured themselves are to be excluded from an oath, because the greatest reverence must be shown to an oath, and from their past deeds it is presumed that they will not show the reverence due to an oath. Likewise, children before the years of puberty are not to be compelled to it, because they do not yet have the perfect use of reason by which they might know how to show the reverence due to an oath. Likewise persons of great dignity, because an oath is required from those concerning whose word or deed there is doubt; and it derogates from men of great authority that the truth of what they say should be doubted. Hence also in the Decretals, question 2, chapter 4, it is said that a priest ought not to swear for a slight cause. Now the causes for which it is lawful to swear are these: for the confirming of peace, as Laban swore, Gen. 31:44 and following; second, for the preserving of one's reputation; third, for keeping fidelity, as vassals swear to their lords; fourth, for fulfilling obedience, if something honorable is commanded by a superior; fifth, for making security; sixth, for attesting the truth. Thus the Apostle swore, Rom. 1:9: "God is my witness," et cetera. Then, when he says, "and of all controversy," etc., he sets forth the effect of the oath, which consists in this: that through an oath every controversy is ended. For just as in the sciences, when the analysis is resolved back to the first demonstrable principles, one comes to rest, so it has been introduced by divine law that when one arrives at the first truth there is a standing point, which happens when that truth itself is called to witness. Ex. 22:8: "He shall be brought to the gods, and shall swear," and thus every question and controversy is put to rest. Then, when he says, "wherein more abundantly," he sets forth the reason why God wished to swear, namely, to show the firmness of his promise. Hence he says "wherein," that is, by that very fact God interposed an oath, wishing more abundantly to show, et cetera. For it was abundant that he promised, but it was more abundant that he swore. Wishing, I say, to show to the heirs the promise, that is, of the thing promised. Rom. 9:8: "They who are the children of the promise are counted for the seed." To show, I say, the immutability. It must be known that in those things which proceed from God, two things are to be considered: namely, the process itself of things, and the counsel of God from which such a process is caused. The counsel of God is altogether immutable. Is. 46:10: "My counsel shall stand, and all my will shall be done." But the disposition is indeed mutable. For the Lord sometimes pronounces something according to what the order and process of things demands, as is clear, Is. 31: "Set your house in order, for you shall die, and not live." For he had the course of his illness, from which he would die. And likewise Jonah 3:4: "Yet forty days, and Nineveh shall be destroyed," because it had deserved its own destruction. Jer. 18:7-8: "I will suddenly speak against a nation, and against a kingdom, to root it up, and to pull it down, and to destroy it. If that nation shall repent of its evil, which I have spoken against it, I also will repent of the evil that I had thought to do to it." And then the prophecy is one of threat. But sometimes something is pronounced insofar as it regards the eternal counsel of God, and concerning this God never repents, nor does he withdraw it. 1 Kings 15:29: "The triumpher in Israel will not spare, and will not be bent by repentance." Yet it must be known that whenever the Lord promises something under oath, it is a prophecy of predestination, which is disclosive of the divine counsel; and this promise is utterly immutable. Then, when he says, "that by two things," etc., he shows the fruit of the promise: and first he shows what that fruit is; second, who obtains this fruit, at the place, "which as an anchor." Now the fruit is that our hope should be certain: hence he says, "that we may have" a most strong, that is, most firm, comfort of hope, through two immutable things, in which it is impossible to lie — namely, through God, who promises, who does not lie, Num. 23:19: "God is not as the son of man, that he should lie," and through the oath, in which there is a greater confirmation of the truth. Now it must be known that just as sensible delight is from sense experience, and memory is of the past, so hope is of the future. 1 Mach. 2:61: "All that hope in him shall not be weakened." Is. 40:31: "They that hope in the Lord shall renew their strength, they shall take wings as eagles, they shall run and not labor," et cetera. "That we may have," I say, we who flee from evils, namely of the world, and from the assault of the enemy, so as to hold fast the hope set before us. Ps. 89:1: "Lord, you have been our refuge." Prov. 18:10: "The name of the Lord is a most strong tower; the just runs to it, and shall be exalted." Then, when he says, "which as an anchor," he shows that the faithful obtain this promise, and he makes use of a certain likeness. For he compares hope to an anchor, which, just as it holds a ship immovable at sea, so hope firms the soul in God in this world, which is, as it were, a certain sea. Ps. 103:25: "This sea, great and wide of hand." Yet this anchor must be secure, so that it does not fail. Hence it is made of iron. 2 Tim. 1:12: "For I know whom I have believed, and I am certain," et cetera. Likewise it must be firm, so that it is not quickly removed from the ship: thus a man must be bound to this hope, just as an anchor is bound to a ship. But there is a difference between an anchor and hope, because an anchor is fixed in the depth below; but hope is fixed on high, namely in God. For nothing in the present life is firm, where the soul could be made firm and rest. Hence Gen. 8:9 says that the dove did not find where its foot might rest. And therefore he says that it must go in as far as the inner side of the veil. For by the "holy places," which were in the tabernacle, the Apostle understands the present state of the Church; but by the "holy of holies," which was distinguished from the holy places by the veil, he understands the state of future glory. In that, therefore, he wishes the anchor of our hope to be fixed, which is now veiled from our eyes. Is. 64:4: "Eye has not seen, O God, besides you, what you have prepared for them that wait for you." Ps. 30:19: "How great is the multitude of your sweetness, O Lord, which you have hidden for them that fear you." This anchor our forerunner has fixed there, who has entered there. Hence Jn. 14:2: "I go to prepare a place for you." Micah 2:13: "He ascended, opening the way to them." And therefore he says that he, as a forerunner, entered for us into the inner side of the veil, and there fixed our hope, as is said in the collect, on the vigil, and on the day of the Ascension. Yet because it was not lawful to enter within the veil except for the high priest alone, Lev. 16:2, therefore he says that Jesus, who entered for us, was made a high priest forever according to the order of Melchizedek. Behold how elegantly the Apostle returns to his purpose. For he had begun to speak of the priesthood, and yet had digressed a great deal; but now he returns to it, as is clear.”

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“Which hope we have as an anchor of the soul,.... This world is as a sea; the church in it, and so every believer, is as a ship; the port that is bound unto is heaven; Christ is the pilot, and hope is the anchor: an anchor is cast on a bottom, out of sight; and when the ship is in a calm, or in danger of a rock, or near the shore; but is of no service without a cable: and when cast aright, keeps the ship steady: so hope is cast on Christ; whence he is often called hope itself, because he is the ground and foundation of it, and who is at present unseen to bodily eyes; and the anchor of hope without the cable of faith is of little service; but being cast aright on Christ, keeps the soul steady and immovable: in some things there is a difference between hope and an anchor; an anchor is not of so much use in tempests as in a calm, but hope is; the cable may be cut or broke, and so the anchor be useless, but so it cannot be with faith and hope; when the ship is at anchor, it does not move forward, but it is not so with the soul, when hope is in exercise; the anchor of hope is not cast on anything below, but above; and here it is called the anchor of the soul, to distinguish it from any other, and to show the peculiar benefit of it to the soul. Pythagoras makes use of the same metaphor (x); "riches (he says) are a weak anchor, glory: is yet weaker; the body likewise; principalities, honours, all these are weak and without strength; what then are strong anchors? prudence, magnanimity, fortitude; these no tempest shakes.'' But these philosophical moral virtues are not to be compared with the Christian's grace of hope, which is both sure and steadfast; it is in itself a grace firm and stable; it is permanent and can never be lost: and it is still more sure and steadfast, by virtue of what it is fixed upon, the person, blood, and righteousness of Christ; and by the immutability, faithfulness, and power of God it is concerned with; and through the aboundings and discoveries of divine love, grace, and mercy; and from the instances of grace to the vilest of sinners: and which entereth into that within the vail; the holy of holies, heaven itself; in allusion to the vail which divided between the holy and the holy of holies: the things within the vail, or in heaven, which hope entering into fixes upon, are the person of Christ, who is entered there, and appears in the presence of God for his people; his blood which he has carried along with him, and by which he is entered there; his justifying righteousness, by which the law is fulfilled, the two tables of stone in the ark of the testimony; the sweet incense of his mediation, which is continually offered up by him; the mercy seat, or throne of grace, on which Jehovah sits as the God of grace; and all the glories of heaven; all which hope is concerned with, and receives strength and rigour from: and their being within the vail, is expressive of their hiddenness and invisibility at present, and of their safety and security, as well as of their sacredness; and this shows a difference between the hope of believers and others, whose hope fixes upon things short of these; and likewise the great privilege of a believer, who being made a priest unto God, has liberty and boldness to enter into the holiest of all. The Jews (y) speak of a vail in the world to come, which some are worthy to enter into. (x) Apud Stobaeum, Serm. I. (y) Zohar in Gen. fol. 73. 3.”
Source
1832
A.D.
Adam Clarke Methodist
1762–1832
“That by two immutable things - The promise and oath of God: the promise pledged his faithfulness and justice; the oath, all the infinite perfections of his Godhead, for he sware by himself. There is a good saying in Beracoth on Exo 32:13, fol. 32: Remember Abraham, Isaac, and Israel, thy servants, to whom thou swarest by thine own self. "What is the meaning of by thine own self? Rab. Eleazar answered, Thus said Moses to the holy blessed God, Lord of all the world. If thou hadst sworn to them by the heavens and the earth, then I should have said, As the heavens and the earth shall pass away, so may thy oath pass away. But now thou hast sworn unto them by thy great name, which liveth, and which endureth for ever, and for ever and ever; therefore thy oath shall endure for ever, and for ever and ever." This is a good thought; if God had sworn by any thing finite, that thing might fail, and then the obligation would be at an end, but he has sworn by what is infinite, and cannot fail; therefore his oath is of eternal obligation. We might have a strong consolation - There appears to be an allusion here to the cities of refuge, and to the persons who fled to them for safety. As the person who killed his neighbor unawares was sure if he gained the city of refuge he should be safe, and had strong consolation in the hope that he should reach it, this hope animated him in his race to the city; he ran, he fled, knowing that, though in danger the most imminent of losing his life, yet, as he was now acting according to an ordinance of God, he was certain of safety provided he got to the place. It is easy to apply this to the case of a truly penitent sinner. Thou hast sinned against God and against thy own life! The avenger of blood is at thy heels! Jesus hath shed his blood for thee, he is thy intercessor before the throne; flee to him! Lay hold on the hope of eternal life which is offered unto thee in the Gospel! Delay not one moment! Thou art never safe till thou hast redemption in his blood! God invites thee! Jesus spreads his hands to receive thee! God hath sworn that he willeth not the death of a sinner; then he cannot will thy death: take God's oath, take his promise; credit what he bath spoken and sworn! Take encouragement! Believe on the Son of God, and thou shalt not perish, but have everlasting life!”
Source
1863
A.D.
1871
A.D.
1871
“immutable--Translate, as in Heb 6:17, "unchangeable." impossible . . . to lie--"ever to lie"; this is the force of the Greek aorist [ALFORD]. His not being able to deny Himself is a proof, not of weakness, but of strength incomparable. consolation--under doubts and fears, and so "encouragement," literally, "exhortation." fled for refuge--as if from a shipwreck; or, as one fleeing to one of the six cities of refuge. Kadesh, that is, holy, implies the holiness of Jesus, our Refuge. Shechem, that is, shoulder, the government is upon his shoulder (Isa 9:6). Hebron, that is, fellowship, believers are called into the fellowship of Christ. Bezer, that is, a fortress, Christ is so to all who trust in Him. Ramoth, that is, high, for Him hath God exalted with His right hand (Act 5:31). Golan, that is, joy, for in Him all the saints are justified and shall glory. lay hold upon the hope--that is, the object of our hope, as upon a preservative from sinking. set before us--as a prize for which we strive; a new image, namely, the race course (Heb 12:1-2).”
Source
Modern · 1953 →

The in-app commentary runs from the Fathers to the early-modern record, then stops — that's where the public-domain sources end, not where the reading does. For the modern reading, follow the sources directly.