Many years ago I came across--what I continue to consider to this day to be--the most interesting tract I've seen. Taking first place in the evangelistic tract category is actually not all that difficult since most tracts are horribly predictably and uncreative. If ever believers have ignored the admonition of our Lord Jesus to "be wise as serpents" it is in the tract-writing ministry department. Though the cover art of the tract that grabbed my attention was as aesthetically unappealing as the content of the majority of tracts that I've read, the message of this tract was striking. The front of the tract had the title, "Four Things God Cannot Do." If I remember correctly, the four things were:
1. God cannot tolerate evil.
2. God cannot accept any solution except the saving work of His Son, Jesus.
3. God cannot reject anyone who comes in the name of Jesus.
4. God cannot take second place in your life.
I used to give this tract out on the boardwalk in Wildwood, NJ where my wife and I did evangelistic ministry for several summers. I loved watching the expressions of people as they looked down at the tract. Some would turn to their friends and say, "See, I was right. (apparently having told their friend that there was no all-powerful being)." Others would ask, "So, are you an anti-Christian group?" It served the shock-value purpose of capturing the interest--if only long enough to get people to open the tract and read it. While it is a bit of an overstatement to say that there are four things that God cannot do (categorically, there is really only one thing God cannot do--He cannot change and go against His nature), the writer of Hebrews (Heb. 6:13-20) explicitly speaks of two things that God cannot do: (1) He cannot lie about the word of His promise, and (2) He cannot lie with regard to the oath of His covenant. Of course, these two things are really two aspects of the unchangeableness of God.
The writer of Hebrews, while exhorting the Hebrew believers as to the danger against apostasy, turns and encourages those who professed faith to trust the Covenant God who made a promise to Abraham and then confirmed it by the oath. It is ultimately not the resolve of the believe that establishes him or her; it is the sure and steadfast promises of God--and accomplishment of those promises in Christ--that is the sure foundation of the believers hope and perseverance. We get something of the need that believers have for the repetition of these promises from the Genesis narrative of God's dealing with Abraham. God came to Abraham and gave him "exceedingly great and precious promises" (Gen. 12:1-3). He then reiterated and developed those promises, time and time again, as He carried Abraham along in faith. John Owen put it so well when he wrote: "God redoubled the word at the first giving of His promise unto Abraham, for the strengthening of his faith." God still does this today. Again Owen noted: "We need everything that any way evidences the stability of God's promises to...us, for the encouragement of our faith." God not only reiterated His promises, He swore by Himself. In the truest and fullest sense of the phrase, "He swore to God." God swore by Himself that He would fulfill everything that He promised to Abraham. The Apostle Paul retrospectively looks back on the promises made to Abraham and says, "All the promises of God are 'Yes' and 'Amen' in Christ" (2 Cor. 1:20).
As if God giving a promise on the integrity and greatness of His own being were not enough, He then entered into a covenant making oath arrangement in the cutting of the animals (Gen. 15:7-21). In the Ancient Near East, two parties would enter into a covenant arrangement by taking a number of animals, cutting them apart and then walking through the middle of the cut animals. In this way, the parties in the covenant were saying, "If I break this covenant may God do so to me" (Jer. 34:18). In the case of God's promises to Abraham, it was not Abraham and God who walked through the cut animals. Rather, it was God and God who walked through. God was representing Abraham (and the elect) together with Himself (Gen. 15:17-18). The LORD charged Abraham, "Walk before Me and be blameless" (Gen. 17:1). On several occasions we are told that Abraham did not walk before God blameless. On two occasions Abraham sold his wife into the hands of kings whom he feared. Instead of waiting on God to fulfill His promise Abraham took it into his own hands by going into Hagar for a child. Since Abraham, and we, have broken the legal demands of the covenant (perfect and perpetual obedience) then the curses of the covenant must truly be inflicted. This is the point of the cutting apart of the animals. Just as circumcision (which was given to Abraham) represented that God would "cut off" from His presence those who break the covenant, so it was with the symbolism of the cutting of the animals. Since God represented Abraham (and all subsequent believers) when He passed through the cut pieces, God would take the curses on Himself. That's what we see at the cross. On the night when He was betrayed our Lord Jesus took bread and broke
it. This was symbolizing what would happen to Him on the cross. Even as the animals were cut apart, so Jesus was "cut off from the land of the living" at Calvary. He was "wounded for our transgressions; crushed for our iniquities. When it's said that Abraham "did not waver in unbelief" we understand that the blood of Jesus covered Abraham's times of evident unbelief.
The promise-making God is the promise-keeping God who does not and cannot change (Mal. 3:6; Heb. 6:18). In this, we who do change, are kept. The confidence we ought to have in the unchangeable promise of God is unmeasurable. It is limited only by the infinitude of God Himself. Owen again drew out the conclusion of the matter when he wrote: "Where the promise of God is absolutely engaged, it will break through all difficulties and oppositions unto a perfect accomplishment." We ought to be able to face any trial, and any difficulty without wavering. This is what the Scriptures said was true of Abraham. "No unbelief made him waver concerning the promise of God, but he grew strong in his faith as he gave glory to God, fully convinced that God was able to do what he had promised" (Rom. 4:20-21).
The believer, like Abraham, must take the promises of God and face the challenges of life that sometimes seem to run counted those promises. We are told Abraham knew that God had promised to bless the nations in Isaac (as the type Christ), but then he was told to sacrifice Isaac. The writer of Hebrews tells us that "Abraham reasoned that God could raise Isaac from the dead" (Heb. 11:19). How important sanctified reasoning is to Christian perseverance! God brings difficult trails into our lives so that we learn to live by faith in the promises. Sinclair Ferguson helpfully suggests that "we're all patient when we have no frustrations; but the very essence of patience is that we're able to cope with, bear the burden of and see through frustrations. And here's one of the great paradoxes of God's ways with us. God is determined to be frustrating to you; because unless He is frustrating to you, at the end of the day, you'll begin to confuse your will for your life with God's will for you life." Abraham held onto the promises even when they seemed contrary to the further commands and providences of God. We too will persevere by faith in those promises. Since those promises have all been fulfilled in Jesus Christ, the writer of Hebrews rightly calls Him "the anchor of our souls." If our souls are anchored to the One who Himself fulfilled the demands of the covenant and took the punishment for our sins in order to fulfill the promises, nothing and no one can shake that foundation. What would it take for those savingly united to Christ to fall away from Him? Thomas Peck explained:
"When Christ can be degraded from His position at the right hand of the Majesty on high, when He can be made to abdicate His supremacy over principalities and powers, and might and dominion, and to become again a wanderer among sinful men, the object of their reproach, and finally the victim of their malignity; when the Father can forget His acceptance of the work of His own Son, an acceptance so solemnly proclaimed in raising him from the dead and giving him glory; then, and not before then, can one who has been united to Christ become subject to the penalty of the law, and expiate that penalty in the everlasting pains of hell. 'The gifts and the calling of God are without repentance.' 'He is not a man that He should lie, or a Son of man that He should repent.' 'He who has begun a good work in us will perform (or finish) it until the day of Christ Jesus.'"
You can listen to or watch the sermon in which I attempt to preach the glorious truths of Heb. 6:13-20 here