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Main Idea: Hebrews 3:7-19 exhorts us to get serious about dealing with the sin of unbelief. We’ll take two weeks to ponder this serious warning about a sin we tend to overlook. This morning, in verses 7-13, we’ll look at this sin from two perspectives.

It’s one of our biggest foes, but most of us probably seldom give serious thought to the fact that it is a foe. We’re much more prone to think that our biggest problems are actions, such as our own actions where we fail to do as we ought, or hurtful actions by others. But action sins begin somewhere else, don’t they? There’s something that precedes sins of action.

I’m talking about the sin of unbelief. Unbelief is a serious problem, yet it’s probably not even on our top ten list. What is the sin of unbelief? Fundamentally, it’s the failure to believe God. We could make a strong case that every other sin boils down to the sin of unbelief.

A college student looks at pornography on his computer in his dorm room. He commits the sin of fornication in his mind. Yet accompanying this sin is another, more fundamental sin, one that makes the mental fornication possible. And that is his tolerance of the sin of unbelief. This young man really doesn’t believe God is there, for if he did he surely wouldn’t be visiting those websites, not with God watching. He certainly doesn’t want his roommate to see him viewing pornography, and because he believes his roommate exists and that there may be shame if his roommate knew the truth, he avoids those sights when his roommate is present. But when he’s all alone, it’s a different story. And that’s the problem. He thinks, he lives like he is all alone in that room. So for all practical purposes, he doesn’t believe God exists, at least not at that moment and not in that room. Oh, he may have sung loud praises to God at his church on Sunday, but there in his room on Monday he has become a practical atheist.

And the sin of unbelief underlies a host of other sins. Think of the middle-aged woman who uses her vicious tongue to tarnish reputations. Behind her sins of slander and gossip lies the sin of unbelief, for if she truly believed God was present she would not say the hurtful things she says about people.

Think of the child who tells her parent, “I came straight home from school, just like you asked,” even though she didn’t come straight home. What made the sin of lying possible was the presence of the fundamental sin of unbelief, for had this young girl really believed that God existed and that God was omnipresent, would she have lied?

It shows up in more subtle ways too, ways we tend to excuse. Think of the aging person who’s full of anxiety and can’t sleep at night because she’s fearful of the possibility of having to live in a care facility some day. Or of the man who’s irritable with his wife and children because he’s heard a rumor that he may lose his job due to company cutbacks. Has not God promised never to give His people more than they can bear? And has He not promised to be with them and to meet their needs in every situation? Yes, and yet those promises do not help us if we fail to believe them, or to put it more precisely, if we fail to believe Him.

A little over nineteen centuries ago a group of Jewish men and women heard the good news about Jesus the Messiah and of the forgiveness and eternal life that God offered through Him. They gladly embraced Jesus and consequently stopped going to Jerusalem to offer sacrificial lambs. But then the opposition began, from their family members and neighbors who said, “How dare you turn your back on your heritage!” And it got worse when the critical words turned into violent actions, to the point that some of the young followers of Christ began to waver. “Maybe we made a mistake,” they started thinking. “Maybe we should go back to our old ways.”

And so the book of Hebrews was written. Does the Bible offer us help for the sin of unbelief? Yes, indeed! In the first two chapters the writer exalts the supremacy of the person of Jesus Christ, for once you know who Jesus is you’ll see how ludicrous it is not to believe in Him. And then, as we saw last week in Hebrews 3:1-6, the book calls for Jesus-focused-living. In light of who Jesus is—verse 1 says he is the apostle and high priest we confess—we are to “fix our thoughts” on Him.

Yet if Jesus is going to be the hub of our lives (and not just a “spoke” in the wheel), there’s a root sin we’re going to have to address. You got it. The sin of unbelief is one of the biggest foes we must overcome if we’re serious about Jesus-centered-living, and the writer of Hebrews addresses this very sin head-on in the very next passage.

Hebrews 3:7-19 exhorts us to get serious about dealing with the sin of unbelief. We’re going to take two weeks to ponder this grave warning about a sin we’re prone to overlook. This morning, in verses 7-13, we’ll look at this sin from two perspectives.

Verse 7 begins, “So” [‘wherefore’ in the KJV]. “So, as the Holy Spirit says: ‘Today, if you hear his voice…’” The writer begins to quote from Psalm 95:7-11, a text he will cite over and over again in this chapter and the next (see also 3:15, 4:3, 4:5, and 4:7). When he quotes this psalm in 4:7 he acknowledges that David wrote it, but here he attributes it to God the Holy Spirit. That’s of course because God the Holy Spirit worked through human instruments like David to reveal and record the Scriptures (2 Pet. 1:20-21). Never forget that the Scriptures are indeed the Word of God. When we read our Bible or hear it preached we are hearing from God Himself. That’s why it’s a dangerous thing to say, “Oh, I know what the Bible says, but…” Never forget that what the Bible says, God says.

The writer of Hebrews invites us to ponder carefully what the Holy Spirit says in Psalm 95, for there we learn three things about the sin of unbelief.

A. It’s a universal problem (7). “Today, if you hear his voice, do not harden your hearts.” Who is the “you” referring to? As just mentioned, the Holy Spirit revealed this psalm through David, so the “you” is referring to the Israelites who lived in David’s day, ten centuries B.C. That means that folks in David’s day struggled with the sin of unbelief.

But read on. “Today, if you hear his voice, do not harden your hearts as you did in the rebellion, during the time of testing in the desert, where your fathers tested and tried me and for forty years saw what I did.” Who does David have in mind this time? The second “you” is referring to the Jews who lived in Moses’ day, around 1440 B.C., who hardened their hearts to God. Like the Jews in David’s day, so too the Jews in Moses’ day struggled with unbelief.

And so did the Jewish Christians who received the book of Hebrews around A.D. 60. They also struggled with the sin of unbelief, and that’s why the writer confronted them about it here.

But by extension the “you” refers to us, for the Holy Spirit who revealed and preserved Psalm 95 also revealed and preserved the book of Hebrews because this book is for everyone. And that’s because everyone struggles with the sin of unbelief. It’s a universal problem.

Now notice again what the Holy Spirit says to us. He begins with “Today.” The author of Hebrews loves the word “today,” and uses it eight times in the book, three times in this chapter alone (verses 7, 13, & 15).

It’s worth noting that Psalm 95 is a worship psalm. It begins with a call to come, sing, and shout to the Lord (1), to give Him thanks and extol Him with music (2), to bow down and kneel before Him (6). And for these reasons: He is the great God and king (3-5), and He is our God and shepherd (7a).

And then comes the warning in Psalm 95, the warning that the writer of Hebrews cites, “Today, if you hear his voice, do not harden your hearts.” What’s that tell us? Two significant things…

2. Hearing God’s Word is dangerous. It’s good if you hear His invitation to come, sing, shout, give thanks to Him, and so on, if what happens? If…you believe and obey His Word. But what if you don’t? What if you hear it and harden your heart to it? Then, as the rest of Psalm 95 declares, it’s dangerous, very dangerous, for it may cost you your life. So unbelief is a universal problem.

B. It’s a heart problem (8-10). Wiersbe has well observed, “The heart of every problem is a problem in the heart.”[1] As we read verses 7-10, notice that the sin problem for the Israelites began in the heart. In verses 7-8, David says to his people (and by application, to us), “Today, if you hear his voice, do not harden your hearts,” and then looks back for an example to the Jews in Moses’ day in verses 8b-9, “As you did in the rebellion, during the time of testing in the desert, where your fathers tested and tried me and for forty years saw what I did.”[2]

Now notice the core problem, according to God’s assessment in verse 10, “That is why I was angry with that generation, and I said, ‘Their hearts are always going astray, and they have not known my ways.”

The sin of unbelief is an indicator of a heart problem. God said the hearts of His people were unstable. They had fluttering hearts, wandering hearts, off and on hearts, hearts that continually were going astray. And notice how verse 10 says that wandering hearts and linked to not knowing God’s ways. It makes sense, doesn’t it? If you don’t know God’s ways, that is, you don’t know the path He wants you to walk in life, as well as His purposes for taking you on that path (which often includes hardship), then you’ll be inclined to wander from that path, first in your heart and then in your life.

In the Bible, the term “heart” refers to the inner person, the part of you no one can see but God. It includes your thoughts, feelings, and will. That’s where sin begins. That’s where the sin of unbelief begins, in the part of you that no one else sees.

The Israelites had a fundamental problem. They weren’t right with God in the inner man. They didn’t know the ways of God. As Leon Morris explains, “They were not blamed simply for not knowing but for not knowing things they ought to have known and acted on.”[3]

Just think of the Israelites in the wilderness. They murmured over and over again. They weren’t satisfied with God or what He did for them. At Rephidim they had no water and so questioned God’s presence and goodness (Exod. 17:1-7). At Marah they complained because the water was bitter (Exod. 15:23-26). In the Desert of Sin they complained because things weren’t like they were back in

Egypt

where “we sat around pots of meat and ate all the food we wanted” (Exod. 16:3)—talk about short term memory loss! God gave them manna but then the people complained because there was no meat (Num. 11:10ff). It’s unthinkable, yet the Israelites so hardened their hearts that they wanted to go back to Egypt , to return to the land where they had been slaves.

So unbelief is a universal problem and a heart problem. Thirdly, from the example of the Israelites in Moses’ day we learn that…

C. It’s a costly problem (11). “So I declared on oath in my anger, ‘They shall never enter my rest.’”

The Old Testament account of Numbers 14:21-23 gives the fuller version. God is speaking, and says: “Nevertheless, as surely as I live and as surely as the glory of the LORD fills the whole earth, not one of the men who saw my glory and the miraculous signs I performed in Egypt and in the desert but who disobeyed me and tested me ten times— not one of them will ever see the land I promised on oath to their forefathers. No one who has treated me with contempt will ever see it.”

Is unbelief a serious matter? Let there be no doubt about it. We’re given two reasons in Hebrews 3:11…

1. It triggers the anger of God. “So I declared on oath in my anger.” And…

You say, “I thought God was loving. I didn’t know He got angry.” He is loving, but He also exhibits anger. When? Here’s when, when people who see His glory disbelieve and then disobey Him.

You say, “Well then, I’m safe, for I’ve never seen His glory.” Really? Psalm 19:1 says, “The heavens declare the glory of God; the skies proclaim the work of his hands.” Have you ever seen the stars at night? Then you’ve seen the glory of God demonstrated. How did you respond? Did you look at those stars and say, “Almighty God, You are so great! You made all these billions of heavenly lights. You made me, and I praise You!”

Is that how you responded to the demonstration of God’s glory He privileged you to see? How many times do we look at the stars and not even think about God, let alone praise Him for His greatness? And it’s not just the stars. All creation reveals the glory of God (Rom. 1:18-23).

And greatest of all, Jesus Christ reveals the glory of God, for indeed, as Hebrews 1:3 declares, “The Son is the radiance of God’s glory.” This morning, through the proclamation of God’s Word you are once again seeing Christ, and thus you are seeing the very radiance of the glory of God. If it’s unthinkable to look at the night stars and not give God honor for the privilege of seeing His glory, it is the highest of insults to see Christ as He is revealed to us in His Word and then fail to respond in faith and obedience.

Beloved, hear the invitation of Hebrews 3, of Psalm 95. “Today, if you hear His voice, do not harden your hearts.” Every time we hear God’s Word we should respond with a heartfelt, “Yes, I believe that word!” and “Yes, I will obey that word!” and “Yes, I praise You Almighty God for Your grace extended to me through Jesus Christ which makes my faith and obedience possible!”

Or to put it another way, every time you hear God’s Word, place yourself under it, not over it (as a judge), not beside it (as a curious inspector), not away from it (as a spectator), but under it as a humble and grateful servant.

Oh, beloved, the sin of unbelief is so subtle and so serious. In this room right now, behind your smiling face, and your nodding head, and your throat that cries “Amen!” to the Word, is the part of you that nobody but God sees. And it’s there, in our hearts, that we must allow the Spirit of God to have His way.

Allow me to give a very practical suggestion. Every time you are exposed to God’s Word, and I mean every time, whether it’s a sermon in church, or on the radio, or as you’re having your devotions, every time, get intentional and deal with the sin of unbelief by this threefold response: “Lord, I believe that. And Lord, I will obey that. And Lord, I need Your grace through Christ which makes my faith and obedience possible.”

Which brings us to our second perspective. The first is that the Holy Spirit confronted the sin of unbelief. The second is that…

Verses 12-13—“See to it, brothers, that none of you has a sinful, unbelieving heart that turns away from the living God. But encourage one another daily, as long as it is called Today, so that none of you may be hardened by sin’s deceitfulness.” From this brief exhortation we learn that dealing with the sin of unbelief requires that we give our attention to three things.

A. We must give attention to our hearts (12). Listen to verse 12 again, this time from the KJV, “Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God.”

Notice the command, “See to it!” “Take heed!” If we’re going to deal with the sin of unbelief we cannot be passive, and specifically we cannot be passive when it comes to the heart. Know this about your heart, my friend…

2. It produces fruit that everybody sees. Jesus said in Matthew 15:18, “But those things which proceed out of the mouth come forth from the heart; and they defile the man.” Our hearts are key, which is why the writer of Hebrews urges us to give attention to the prevention of three things in our hearts…

See to it that none of you has a sinful heart, an unbelieving heart, and a heart that turns away from the living God. These three characteristics go together. Sin begins in the heart. Sin manifests itself by a life that turns away from God and goes its own way. But it’s this one particular sin that leads the way, the sin of unbelief. Make sure you don’t have an unbelieving heart, says Hebrews.

Hebrews 11:6 makes this bottom-line statement, “And without faith it is impossible to please God, because anyone who comes to him must believe that he exists and that he rewards those who earnestly seek him.” To come to God you and I must believe. But that’s our root problem. We are born with unbelieving hearts.

Very few things amazed Jesus, but this did. Mark 6:6 says, “And he was amazed at their lack of faith.” Do you remember the father in Mark 9 who came to Jesus with his demon-possessed son? Do you remember what he said? Mark 9:22—“If you can do anything, take pity on us and help us?” And do you recall Jesus’ response in Mark 9:23? “‘If you can’? said Jesus. ‘Everything is possible for him who believes.’” And I love the reaction of the dad to Jesus in the very next verse (24), “I do believe; help me overcome my unbelief!”

That’s our fundamental problem, dear friends. We struggle with unbelief. Which is why the Bible calls non-Christians unbelievers, for it sums up the natural man’s approach to life. Thankfully, there’s hope for non-believers, for in His grace God provides us with everything we need to please Him, as Ephesians 2:8 reveals, “For it is by grace you have been saved, through faith—and this not from yourselves, it is the gift of God.”

So we need to do as this father did. “Help me overcome my unbelief!” You can’t be saved without that admission, for apart from God’s grace no sinner will ever believe in Christ. Yet that’s a fitting cry for saved people, too. “Help me overcome my unbelief!”

If we’re going to deal with our unbelief, we must give attention, first and foremost, to our hearts. But there’s more, according to Hebrews 3.

B. We must give attention to each other (13). Look again at verse 12, at something we Americans often miss in our rugged individualism. Notice that this is a corporate responsibility, “See to it, brothers, that none of you has a sinful, unbelieving heart.” The verse says that we must give attention to an assignment (and the present verb tense, “see to it,” indicates continuous action is necessary). The assignment? We need to make sure that none of us has a sinful, unbelieving heart. It’s not just my heart that ought to concern me, but your hearts, too. We’re supposed to be giving attention to each other, and specifically, to each other’s hearts, and specifically, to make sure that no one in our church family is harboring an unbelieving heart that, if left unchecked, will result in that person turning away from God.

You say, “But how would I ever know if my brothers in Christ are tolerating unbelief in their hearts?” That’s a great question! You won’t know the condition of the hearts of your church family members unless you what? Unless you get to know them. And as I mentioned last week, that’s why Sunday morning isn’t enough. That’s why we need to make participating in the life of the church a high priority. That’s true for many reasons, but here are two from Hebrews 3…

1. We can’t make it alone. “Prone to wander, Lord I feel it; prone to leave the God I love.” Can you relate to the words of the hymn-writer? We’re prone to wander, and especially when we isolate ourselves from our church family members. The fact is…

2. We need others to help us see when we’re starting to slide. That’s what verse 12 says. To paraphrase, “Look at each other, brothers, and keep looking! Make sure not a single one of you has a heart that is beginning to waver with doubts and is turning away from God.”

That’s a negative command. It’s something we’re not to let happen. In the next verse, however, in verse 13 we’re given the positive command, and it reveals the third matter to which we must give our attention if we’re to dispel unbelief.

C. We must give attention to the ministry of encouragement. Verse 13—“But encourage one another daily, as long as it is called Today, so that none of you may be hardened by sin’s deceitfulness.”

This is such a practical verse. It shows us one of God’s gracious provisions for dealing with the sin of unbelief. It’s the ministry of encouragement.

Why do we struggle with unbelief? It’s because we can’t see God, right? He’s with us, sure, but since He is a Spirit and we can’t see Him, we’re prone to doubt, to doubt His goodness, to doubt His love, even to doubt His presence.

But here’s the good news. Even though we can’t see Him, we can see His body. We are His Body. We who know Jesus Christ as our Savior and Lord are His body. And He intends to make Himself known to us through our relationships with each other, and specifically through the ministry of encouragement.

1. We need to think about our church family more than once a week. Encourage one another daily. Let that word sink in…daily. God never intended church to be simply a two hour activity on Sunday morning. Church is our identity. And our identity is to affect our lives 24/7. And specifically, the ministry of encouragement is to be a daily aspiration in our lives.

2. We need purposeful involvement in each other’s lives every day. Notice the word “today” again. We’re told to encourage one another daily, as long as it is called today. What’s true about today? Today comes and goes and then it’s gone. Today doesn’t last forever. So if we’re going to accomplish something today, like encouraging one another, then we can’t be passive and reactive. We must be proactive and intentional. We must daily be thinking about ways to get involved in each others lives so as to bring about encouragement.

That card to the shut-in God has placed on your heart won’t get written unless you go buy it (or make it), write it, and stick in the mail. That meal won’t reach your afflicted sister’s table unless you bake it and take it to her. That phone call to your Sunday School classmate you haven’t seen in two Sundays won’t happen unless you pick up the phone. That lunch appointment with the teenager you’ve wanted to thank for the song that blessed you won’t occur unless you put it on your schedule. That new family in the church that you’ve wanted to get to know will still be a family of strangers to you a year from now if you don’t invite them to your home for dinner. And Hebrews says, “Do it today.”

3. We need to find ways to put courage into the hearts of our brothers. That’s what our English word encouragement means, literally “to put courage into.” In the Greek it’s the verb parakaleo, a broad word that covers a wide range of different activities (of the 109 times it appears in the New Testament, it’s translated in the KJV, for instance, ‘beseech’ 43 times, ‘comfort’ 23 times, ‘exhort’ 21 times, ‘desire’ 8 times, ‘pray’ 6 times, and ‘intreat’ 3 times).

I ran Cross Country in the eighth grade and after the season decided that was enough. No more running in the fall for me! The pain wasn’t worth it. And then one evening the following summer I saw a car drive back the third of a mile lane to our house, and out came the Cross Country Coach, Mr. Lehman. A five minute conversation, and I was ready to run again. It’s amazing what a little encouragement will do!

When it comes to encouragement, the bottom line is this. There are a lot of ways to do it, and the need of the situation will determine the proper way, but we need to do it! We need on a daily basis to get intentional about doing things to put courage into the hearts of our brothers and sisters in Christ. But specifically…

4. We need to go after those whose hearts are growing cold. “Encourage one another…so that none of you may be hardened by sin’s deceitfulness.” Did you catch that? Not one should escape the body’s care. Not one should drift away unnoticed. Hughes writes, “If there should be a concern of the individual for the community (‘exhort one another’), there should also be a concern in the community for the individual (‘lest any one of you…’).”[4]

Beloved, my heart is heavy as I ponder this. We have individuals in our church family who are not participating in the life of the church as they once did. They’ve drifted away. Are they responsible for their absence? Yes. Do we have responsibility? Yes. We need to go after them, to encourage them to come back into the fold. But let’s not wait until people are gone to reach out. Far better to put a fence at the top of the cliff than to run an ambulance service at the bottom. Get involved in the ministry of encouragement. Encourage each other to come, not just to Sunday morning worship, but to Sunday School, to our Sunday evening church family night, and to our Wednesday evening ministry night.

And what should motivate us to engage in the ministry of encouragement? It’s not just to keep people in the race. There’s a higher motivation…

5. We need to do this for the sake of Christ. As verse 14 states, “We have come to share in Christ.” That’s what should motivate us. It’s Christ.

We’ll pick it up there next time, for there’s more to be said about dealing with the sin of unbelief. But as we respond to what we’ve learned today…

1. Do I have any unbelief in my heart today? Be honest with yourself. Are you struggling with doubts. There’s hope and help available. Open up to a brother or sister. Search God’s Word together and approach His throne of grace in prayer.

2. Who can I encourage today? Write down the name of the person God puts on your heart, and seek to put courage into that brother’s heart today.

**Note: This is an unedited manuscript of a message preached at Wheelersburg Baptist Church . It is provided to prompt your continued reflection on the practical truths of the Word of God.

[1] Wiersbe, p. 288.

[2] It’s worth noting, as Robert Gromacki points out, “The period of forty years was also the approximate length of time from the Crucifixion to the writing of Hebrews. These believers were also being tested by God (2:18).” Gromacki, p. 64.

[3] Leon Morris, p. 35.

[4] Philip Hughes, p. 148.