Let me hang a bridge between last Sunday’s text and our concern today with the unbelief of anxiety. In Hebrews 3:12, it says, “Take care, brethren, lest their be in any of you an evil heart of unbelief, leading you to fall away from the living God.” And verse 14 says, “For we have shared in Christ, if we hold our first confidence firm to the end.”

In other words, the evidence that you have come to share in Christ — that you are united to him in saving faith — is that you hold that confidence firm to the end. Perseverance in faith is necessary for salvation. When a person is truly converted, the heart is changed so that now life is lived by faith (Galatians 2:20).

The new birth introduces a person into a life of warfare. That warfare is called the “fight of faith” in 2 Timothy 4:7 and 1 Timothy 6:12. And here in Hebrews 3:12 it is called the battle against unbelief. “Take care [that’s the vigilance of battle], brethren, lest there be in you and evil heart of unbelief [there’s the enemy in the warfare], leading you to fall away from the living God [there’s the warning against not taking the warfare seriously].”

In other words, the most basic battle of our life is the battle to believe in the living God, and not to allow our heart to become an evil heart of unbelief. Because if unbelief in the living God gets the upper hand in our life, then the result can be a hardening that makes us unwilling to repent and thus cuts us off from the grace of God.

Now this will not happen to those who are truly in Christ. Those who are truly born of God take the battle seriously, and draw on the power of God to fight it, and win it with persevering faith. That is what God promises. “He who calls you is faithful and he will do it” (1 Thessalonians 5:23).

“Unbelief is the root of evil and the essence of evil.”

The bridge, then, that I want to hang between last week’s text and this week’s text is the truth that beneath our battle against evil in our heart is the battle against unbelief. Unbelief is the root of evil and the essence of evil. All our sinning grows out of unbelief in the living God and what he has said to us in Scripture.

Unbelief as the Root of Anxiety

Now today’s text illustrates this with a specific evil condition of heart, namely, anxiety. Stop for a moment and think how many different sinful actions and attitudes come from anxiety. Anxiety about finances can give rise to coveting and greed and hoarding and stealing. Anxiety about succeeding at some task can make you irritable and abrupt and surly. Anxiety about relationships can make you withdrawn and indifferent and uncaring about other people. Anxiety about how someone will respond to you can make you cover over the truth and lie about things. So if anxiety could be conquered, a lot of sins would be overcome.

But what is the root of anxiety? And how can it be severed? To answer that we go to our text in Matthew 6. Four times in this text Jesus says that we should not be anxious.

1. Matthew 6:25: “Therefore I tell you, do not be anxious about your life.”

2. Matthew 6:27: “And which of you by being anxious can add one cubit to his span of life?”

3. Matthew 6:31: “Therefore do not be anxious.”

4. Matthew 6:34: “Therefore do not be anxious about tomorrow.”

The verse that makes the root of anxiety explicit is Matthew 6:30: “But if God so clothes the grass of the field, which today is alive and tomorrow is thrown into the oven, will he not much more clothe you, O men of little faith?” In other words, Jesus says that the root of anxiety is lack of faith in our heavenly Father. As unbelief gets the upper hand in our hearts, one of the results is anxiety.

So when Hebrews says, “Take heed lest there be in you an evil heart of unbelief,” it includes this meaning: “Take heed lest there be in you an anxious heart of unbelief.” Anxiety is one of the evil conditions of the heart that comes from unbelief. Much anxiety, Jesus says, comes from little faith.

This is the kind of connection we are going to see again and again in the weeks to come. The root of a sinful condition of the heart is unbelief in the living God.

Two Kinds of Disturbed Responses to This Truth

Now I can think of two kinds of disturbed responses to this truth. Let me tell you what they are and then give a biblical response before we go on to the battle against the unbelief of anxiety.

“This Is Not Good News!”

One response would go like this: This is not good news! In fact, it is very discouraging to learn that what I thought was a mere struggle with an anxious disposition is, in fact, a far deeper struggle with whether I believe God or not.

Now my response to this is to agree but then to disagree. Suppose you had been having pain in your stomach and had been struggling with medicines and diets of all kinds to no avail. And then suppose that your doctor tells you after a routine visit that you have cancer in your small intestine. Would that be good news? You say, emphatically not! And I agree.

But let me ask the question another way: Are you glad that the doctor discovered the cancer while it is still treatable, and that indeed it can be very successfully treated? You say, Yes, I am very glad that the doctor found the real problem. Again I agree.

So the news that you have cancer is not good news because having cancer is good. It is good news because knowing what is really wrong is good news, especially when it can be treated successfully.

That’s what it’s like to learn that the real problem behind anxiety is unbelief in the promises of God. It’s not good news because the cancer of unbelief is good. It’s good because knowing what is really wrong is good, especially because unbelief can be treated so successfully by our great physician.

So I want to stress that finding out the connection between our anxiety and our unbelief is in fact very good news, because it is the only way to begin the battle with the real cause of our sin and get the victory that God can give us by the therapy of his word and his Spirit.

“How Can I Have Any Assurance at All?”

There is another possible response to the truth that our anxiety is rooted in our unbelief in God’s promises. It goes like this: I have to deal with feelings of anxiety almost every day; and so I feel like my belief in God must be totally inadequate. So I wonder if I can have any assurance of being saved at all.

Being Faithless Versus Having Faith Attacked

Suppose you are in a car race and your enemy who doesn’t want you to finish the race throws mud on your windshield. The fact that you temporarily lose sight of your goal and start to swerve does not mean that you are going to quit the race. And it certainly doesn’t mean that you are on the wrong racetrack. Otherwise, the enemy wouldn’t bother you at all. What it means is that you should turn on your windshield wipers and use your windshield washer.

“When anxiety strikes, this does’t mean that we are faithless. It means our faith is being attacked.”

When anxiety strikes and blurs our vision of God’s glory and the greatness of the future that he plans for us, this does not mean that we are faithless, or that we will not make it to heaven. It means our faith is being attacked. At first blow, our belief in God’s promises may sputter and swerve. But whether we stay on track and make it to the finish line depends on whether we set in motion a process of resistance. Whether we fight back against anxiety. Will we turn on the windshield wipers and will we use our windshield washer?

The Testimony of Scripture

Psalm 56:3 says, “When I am afraid, I put my trust in thee.” Notice it does not say, “I never struggle with fear.” Fear strikes and the battle begins. So the Bible does not assume that true believers will have no anxieties. Instead, the Bible tells us how to fight when they strike.

For example, 1 Peter 5:7 says, “Cast all your anxieties on him, for he cares about you.” It does not say, you will never feel any anxieties to cast onto God. It says when the mud splatters your windshield and you lose temporary sight of the road and start to swerve in anxiety, turn on your wipers and squirt your windshield washer.

To the One Who Struggles Daily with Anxiety

So my response to the person who has to deal with feelings of anxiety every day is to say: That’s more or less normal. The issue is how you deal with them.

And the answer to that is: You deal with anxieties by battling unbelief. And you battle unbelief by meditating on God’s word and asking for the help of his Spirit. The windshield wipers are the promises of God that clear away the mud of unbelief. And the windshield washer fluid is the help of the Holy Spirit.

Without the softening work of the Holy Spirit, the wipers of the word just scrape over the blinding clumps of unbelief. Both are necessary — the Spirit and the word. We read the promises of God and we pray for the help of his Spirit. And as the windshield clears so we can see the welfare that God plans for us (Jeremiah 29:11), our belief grows strong and the swerving of anxiety smoothes out.

Overcoming Anxiety by Battling Unbelief

Let me close by using some illustrations how battling unbelief overcomes anxiety.

The Pattern of Jesus and Paul

Here in our text, we have the illustration of anxiety over food and clothing. Even in our country with its extensive welfare system, anxiety over finances and housing can be very intense. But Jesus says in verse 30 that this is owing to unbelief: “O you of little faith.” And so this paragraph has at least half a dozen promises in it to battle that unbelief.

“Believe the promises of Jesus, and anxiety will evaporate in the warmth of God’s care.”

For example, at the end of verse 32 he says, “Your heavenly Father knows that you need them all. But seek first his kingdom and his righteousness, and all these things shall be yours as well.” That is a spectacular promise. In everything you do at home and at work, put God’s purposes first, and he will provide all you need to live for his glory. Believe that promise, and financial anxiety will evaporate in the warmth of God’s care.

Paul applied the promise to anxiety in Philippians like this. In 4:6 he says just like Jesus, “Have no anxiety about anything, but in everything by prayer and supplication let your requests be made known to God.” And then in 4:19 he gives the promise like Jesus, “My God will supply every need of yours according to his riches in glory in Christ Jesus.”

Anxieties We May Face

And so we follow today the pattern of Jesus and Paul. We battle the unbelief of anxiety with the promises of God.

• When I am anxious about some risky new venture or meeting, I battle unbelief with the promise: “Fear not for I am with you, be not dismayed for I am your God; I will help you, I will strengthen you, I will uphold you with my victorious right hand” (Isaiah 41:10).

• When I am anxious about my ministry being useless and empty, I fight unbelief with the promise: “So shall my word that goes forth from my mouth; it will not come back to me empty but accomplish that which I purpose, and prosper in the thing for which I sent it” (Isaiah 55:11).

• When I am anxious about being too weak to do my work, I battle unbelief with the promise of Christ: “My grace is sufficient for you, my power is made perfect in weakness” (2 Corinthians 12:9), and “As your days so shall your strength be” (Deuteronomy 33:25).

• When I am anxious about decisions I have to make about the future, I battle unbelief with the promise: “I will instruct you and teach you the way you should go; I will counsel you with my eye upon you” (Psalm 32:8).

• When I am anxious about facing opponents, I battle unbelief with the promise: “If God is for us who can be against us” (Romans 8:31).

• When I am anxious about being sick, I battle unbelief with the promise that “tribulation works patience, and patience approvedness, and approvedness hope, and hope does not make us ashamed” (Romans 5:3–5).

• When I am anxious about getting old, I battle unbelief with the promise, “Even to your old age I am he, and to gray hairs I will carry you. I have made, and I will bear; I will carry and will save” (Isaiah 46:4).

• When I am anxious about dying, I battle unbelief with the promise that “none of us lives to himself and none of us dies to himself; if we live we live to the Lord and if we die we die to the Lord. So whether we live or die we are the Lord’s. For to this end, Christ died and rose again: that he might be Lord both of the dead and the living” (Romans 14:8–9).

• When I am anxious that I may make shipwreck of faith and fall away from God, I battle unbelief with the promise, “He who began a good work in you will complete it unto the day of Christ” (Philippians 1:6). “He who calls you is faithful. He will do it” (1 Thessalonians 5:23). “He is able for all time to save those who draw near to God through him, since he always lives to make intercession for them” (Hebrews 7:25).

And yesterday when Rob and Gail got married, they printed the promises of God in the wedding folder. With these they have and they will fight off the anxiety of all the unknowns of marriage: “And the Lord is the one who goes ahead of you; he will be with you. He will not fail you or forsake you. Do not fear, or be dismayed” (Deuteronomy 31:8).

So I urge you in your warfare, take up the book of God, ask the Holy Spirit for help, lay the promises up in your heart, and battle on. And remember the promise of Proverbs 21:31, “The horse is made ready for the day of battle, but the victory belongs to the Lord.”