The Urgency of Today: Heeding the Warning Text: Hebrews 3:12-19
Introduction: The Wilderness is a Real Place
The Christian life is not a playground; it is a battlefield. It is not a pleasure cruise; it is a long march through the wilderness. The book of Hebrews is written to a group of Christians who were getting tired. They were weary of the march. The memory of Egypt, even with its slavery, was starting to look strangely attractive. The allure of the old ways, the familiar rituals of the temple, was pulling at them. They were tempted to think that this whole Jesus business was perhaps a bit too much, a bridge too far. They were considering turning back.
And so the writer of Hebrews does not offer them a cup of warm milk and a pat on the head. He sounds the alarm. He grabs them by the shoulders and gives them a good shake. He does this by taking them back to a previous generation that faced the same test and failed it catastrophically. He points them to the generation that came out of Egypt under Moses. That generation saw the mighty hand of God part the Red Sea. They ate the bread of angels and drank water from a rock. They had every reason to trust God, and yet, when the moment of decision came at the border of the promised land, they flinched. They gave way to an evil, unbelieving heart.
We modern Christians have a tendency to read these Old Testament stories as though they were quaint fables, cautionary tales about somebody else. We think, "How could they have been so foolish?" But the writer of Hebrews will not let us off the hook so easily. He says their story is our story. Their temptation is our temptation. The wilderness is not just a place on an ancient map; it is a spiritual reality that every generation of God's people must pass through. And the central danger in that wilderness is not external opposition, but internal rot. The great enemy is not the giants in the land, but the unbelief in our hearts.
This passage is a severe mercy. It is a loving, pastoral, urgent warning. It teaches us that faith is not a one-time decision, but a daily battle. It teaches us that sin is not a harmless pet, but a cunning deceiver that wants to harden our hearts into stone. And it teaches us that the primary means God has given us to fight this battle is one another. We are to be a community of exhorters, constantly pointing each other back to the voice of God, which speaks to us, not yesterday, not tomorrow, but "Today."
The Text
See to it brothers, that there not be in any one of you an evil, unbelieving heart that falls away from the living God. But encourage one another day after day, as long as it is still called “TODAY,” so that none of you will be hardened by the deceitfulness of sin. For we have become partakers of Christ, if we hold fast the beginning of our assurance firm until the end, while it is said, “TODAY IF YOU HEAR HIS VOICE, DO NOT HARDEN YOUR HEARTS, AS WHEN THEY PROVOKED ME.” For who provoked Him when they had heard? Indeed, did not all those who came out of Egypt led by Moses? And with whom was He angry for forty years? Was it not with those who sinned, whose corpses fell in the wilderness? And to whom did He swear that they would not enter His rest, but to those who were disobedient? So we see that they were not able to enter because of unbelief.
(Hebrews 3:12-19 LSB)
The Root of Apostasy (v. 12)
The warning begins with a direct and personal command, aimed at the heart.
"See to it brothers, that there not be in any one of you an evil, unbelieving heart that falls away from the living God." (Hebrews 3:12)
The command is "See to it." This is a call for diligent, active vigilance. This is not passive. We are to be on guard duty. And what are we guarding against? An "evil, unbelieving heart." The Bible diagnoses the root problem of apostasy. People do not drift away from God because of intellectual difficulties or because Christianity became inconvenient. They fall away because of a moral problem, an evil heart, that manifests itself as unbelief. Unbelief is not an intellectual posture; it is a moral rebellion. It is the refusal to trust what God has plainly said. It is choosing to believe the serpent's hiss over the Father's promise.
Notice the connection: an unbelieving heart is what "falls away from the living God." The Greek word for "falls away" is where we get our word apostasy. This is not about having a bad day or a season of doubt. This is a deliberate turning away, a departure. And it is a departure from the "living God." This is not a rejection of some abstract philosophical principle. It is a personal insult to the living, breathing, speaking God of the universe. To turn from Him is to turn from life itself. It is to walk out of a well-lit feast into the outer darkness.
The Community as Cure (v. 13)
But this guard duty is not a solo mission. God's prescribed remedy for the private disease of unbelief is the public ministry of the saints.
"But encourage one another day after day, as long as it is still called “TODAY,” so that none of you will be hardened by the deceitfulness of sin." (Hebrews 3:13)
The antidote to the evil heart is mutual encouragement. The word "encourage" can also be translated "exhort." It is not just about making each other feel good. It is a robust, bracing summons to stand firm, to keep believing, to keep marching. And this is a daily duty. "Day after day." This is not a once-a-week pep talk in the Sunday sermon. This is the constant, ongoing, informal ministry of every Christian to every other Christian. We are our brother's keeper.
The urgency is highlighted by the phrase "as long as it is still called 'TODAY.'" The time to hear God's voice and respond is always now. The devil's favorite word is "tomorrow." But the Holy Spirit's word is "Today." Procrastination in the spiritual life is deadly, because while you are delaying, something else is at work: the deceitfulness of sin.
Sin is a liar. It never presents itself as it truly is. It promises pleasure but delivers bondage. It promises freedom but forges chains. It promises life but its wages are death. And its primary strategy is to harden. Like water dripping on a stone, sin slowly, imperceptibly, erodes our sensitivity to God. At first, the conscience screams. Then it whispers. Then it goes silent. The heart becomes calloused, unresponsive, hard. And the only way to prevent this hardening is to be in a community where the Word of God is constantly being spoken into our lives by our brothers and sisters, keeping our hearts soft and responsive to the Lord.
The Evidence of Perseverance (v. 14-15)
The writer now connects this daily perseverance with our fundamental identity in Christ.
"For we have become partakers of Christ, if we hold fast the beginning of our assurance firm until the end, while it is said, 'TODAY IF YOU HEAR HIS VOICE, DO NOT HARDEN YOUR HEARTS, AS WHEN THEY PROVOKED ME.'" (Hebrews 3:14-15)
This is a crucial verse for understanding the doctrine of assurance. Our perseverance is not the cause of our salvation, but it is the evidence of it. How do we know we have "become partakers of Christ"? By the fact that we "hold fast... until the end." True faith is a faith that lasts. A faith that fizzles out was never true faith to begin with. It was the seed that fell on rocky ground; it sprang up quickly but had no root.
This is not to say that true Christians never struggle or doubt. But it is to say that God, by His grace, will cause His true children to persevere through those struggles. The one who is truly united to Christ will be held by Christ. Our holding on to Him is the evidence that He is holding on to us. This is why the warning is so potent. If you are tempted to let go, it is a sign that you need to examine whether you ever truly had a grip in the first place. The warning itself is one of the means God uses to keep His saints holding fast.
And again, the writer immediately repeats the refrain from Psalm 95. The test is always "Today." The command is always "Do not harden your hearts." The danger is always provoking God through unbelief, just as the Israelites did.
A Case Study in Apostasy (v. 16-19)
The writer concludes this section by driving the historical example home with a series of rhetorical questions. He wants his readers to see themselves in the story.
"For who provoked Him when they had heard? Indeed, did not all those who came out of Egypt led by Moses? And with whom was He angry for forty years? Was it not with those who sinned, whose corpses fell in the wilderness? And to whom did He swear that they would not enter His rest, but to those who were disobedient? So we see that they were not able to enter because of unbelief." (Hebrews 3:16-19)
The answer to his first question, "who provoked Him?" is devastating. It was not a small faction. It was "all those who came out of Egypt led by Moses," with the notable exceptions of Joshua and Caleb. This was the covenant community. These were the people who had been baptized in the Red Sea and had eaten the spiritual food in the wilderness. They had all the external privileges, but they did not mix what they heard with faith.
The consequences were dire. God was angry with them for forty years. Their sin led to their death; their "corpses fell in the wilderness." Their disobedience meant that God swore an oath that they would not enter His rest. They died on the wrong side of the Jordan River, looking at the promise from a distance but never possessing it.
And the writer lands the final, diagnostic punch in verse 19. Why did this happen? Was God unfaithful? Was the promise defective? No. "So we see that they were not able to enter because of unbelief."
Unbelief is the great barrier to God's blessing. It is the sin that locks the door to the promised land. Notice the interchangeability of "disobedient" in verse 18 and "unbelief" in verse 19. In the Bible's dictionary, these are synonyms. To disbelieve God is to disobey Him. And to disobey God is to disbelieve Him. All sin is rooted in a failure to take God at His word. When Eve took the fruit, she was not just breaking a rule; she was believing the serpent's word over God's Word. She was acting on unbelief.
This is the solemn warning for the church in every age. It is possible to be in the church, to sing the songs, to hear the sermons, to be part of the external covenant community, and still have an evil, unbelieving heart. It is possible to come right up to the border of the promised land and yet have your corpse fall in the wilderness. The issue is not your external location, but the internal condition of your heart.
Conclusion: Enter His Rest
The message of this passage is sobering, but it is not meant to lead us to despair. It is meant to lead us to diligence. It is a call to take our faith seriously, to take sin seriously, and to take our fellowship with one another seriously.
Do you feel your heart growing cool? Are there areas of your life where the deceitfulness of sin is whispering its lies, telling you that God's way is too hard, that compromise is no big deal? The command to you is "Today, if you hear His voice, do not harden your heart." Do not wait. Repent now. Turn back to the living God now.
And do not try to do it alone. Find a brother or sister and ask them to encourage you, to exhort you. Be the kind of Christian who is in the lives of others, speaking the truth in love, helping them to hold fast. The Christian life is a team sport. We are roped together on the side of a mountain, and we are responsible to help one another make it to the summit.
The generation in the wilderness failed to enter God's rest because of unbelief. But the good news of the gospel is that a better rest remains for the people of God (Hebrews 4:9). This rest is found in the finished work of Jesus Christ. He is our Joshua who leads us into the true promised land. By faith in Him, we cease from our own works and rest in His. But that faith must be a living, active, persevering faith. Let us, therefore, fear lest any of us should seem to have failed to reach it. Let us exhort one another daily, as long as it is called "Today," lest we be hardened by the deceitfulness of sin and fall short of that glorious rest.