18 that by two immutable things, in which it is impossible for God to lie, we might have strong consolation, who have fled for refuge to lay hold of the hope set before us.
God promised Abraham and his descendants that they would be as innumerable as the stars of heaven and sands of the sea (Ge 15:4-5). Later He confirmed this promise with an oath (Ge 22:16-18). Both His promise and His oath were unchangeable. These two immutable dynamics gave Abraham and his progeny assurance of a future.
The “that” shows the purpose of God’s oath. Since God guarantees His promises by an oath (He 6:17), the recipients of those promises can be encouraged or consoled (He 4:16). They receive this encouragement by the coming of Christ to pay for sin and provide assets for godly living (He 6:19-20).
The “that” demonstrates the purpose God had in mind was to give “strong consolation” to believers under duress. He wants believers to be perfectly clear about His purpose for them; He wanted them to maintain confidence while they waited for His promises to be fulfilled.
by two immutable [unchangeable] things,
The “two immutable things” are 1) God’s promise and 2) His oath that guarantees it. “Immutable” again means unchangeable. There is no possibility to change these irrevocable dynamics. God ratifies His promises by two unchangeable things, a promise and an oath.
in which it is impossible for God to lie,
Since it is impossible for God to lie, we can count on His truthfulness. His immutable character demands it. It is impossible for God’s word to be proven false because of its double establishment by a promise and an oath. God is truth itself, therefore He cannot lie.
We can count on God’s promises.
Since it is impossible for God to lie both His promise and oath will come to pass. Because God does not lie or deceive and is all-powerful, we can count on His promises. He cannot violate His own integrity (2 Ti 1:13). This is what gave Abraham encouragement and assurance. God is the personification of truth (Nu 23:19; 1 Sa 15:29; Ps 33:11; Isa 46:10-11; Mal 3:6; Jas 1:17). His Word can be trusted. We can trust Him because His nature is unchangeable.
God’s promise of hope will not deceive those who trust in it. It is certain to be fulfilled because it is the sure Word of God. God’s proof of fulfillment lay in that He gave both a promise and an oath found in the book of Genesis. Our blessings will be fully realized. Christian hope is based on an eternal order, not a temporal order. This is the believer’s encouragement.