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The Danger of Sins and the Blessing of Christian Community

October 8, 2025

Teacher: John McLeod
Scripture: Hebrews 3:12-14

Introduction — Danger!!

What is a dangerous situation you’ve been in before?

  • What was the danger?

  • Did someone warn you? How?

  • What would have been the consequences if you had not been warned of the danger?

Examples:

  • Nantahala River // Falls

  • Grand Canyon // Edge

Have you ever warned another person of danger?

  • What did you see or know that the other person didn’t see or know?

  • How did you warn the other person?

  • Did you try to convince them of the danger, or simply try to get them to trust you? Why?

Minefield (this is the game for tonight)

  • blindfolded or with reality-distorting glasses

  • with noise-cancelling headphones with music blasting

I. The Dangers of Sin

We know the biggest danger of sin. 

Romans 5:12 (ESV) — Therefore, just as sin came into the world through one man, and death through sin, and so death spread to all men because all sinned—

Romans 6:23 (ESV) — For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord.

Once we become a Christian, the greatest danger of sin is removed. Should we still be concerned? Why?

Reading

Hebrews 3:12–14 (ESV)

  • (12) Take care, brothers, lest there be in any of you an evil, unbelieving heart, leading you to fall away from the living God. 

  • (13) But exhort one another every day, as long as it is called “today,” that none of you may be hardened by the deceitfulness of sin. 

  • (14) For we have come to share in Christ, if indeed we hold our original confidence firm to the end.

A. Sin’s Effect: Harden You

Illustration

  • Hardening of the arteries

  • Hard gum

  • Hard bread

  • Hard, cracking rubber pipes?

  • Hard soil makes it hard to grow some kinds of plants. It also makes it hard to dig holes.

  • Hard cheese

  • Hard clay. You can’t shape it into what you want to make.

  • callouses — keep you from feeling pain.

Why is this dangerous?

Romans 2:5 (ESV) — But because of your hard and impenitentheart you are storing up wrath for yourself on the day of wrath when God’s righteous judgment will be revealed.

Ephesians 4:18 (ESV) — They are darkened in their understanding, alienated from the life of God because of the ignorance that is in them, due to their hardness of heart.

Zechariah 7:8–14 (ESV)

  • (8) And the word of the LORD came to Zechariah, saying, 

  • (9) “Thus says the LORD of hosts, Render true judgments, show kindness and mercy to one another, 

  • (10) do not oppress the widow, the fatherless, the sojourner, or the poor, and let none of you devise evil against another in your heart.” 

  • (11) But they refused to pay attention and turned a stubborn shoulder and stopped their ears that they might not hear. 

  • (12) They made their hearts diamond-hard lest they should hear the law and the words that the LORD of hosts had sent by his Spirit through the former prophets. Therefore great anger came from the LORD of hosts. 

  • (13) “As I called, and they would not hear, so they called, and I would not hear,” says the LORD of hosts, 

  • (14) “and I scattered them with a whirlwind among all the nations that they had not known. Thus the land they left was desolate, so that no one went to and fro, and the pleasant land was made desolate.”

Proverbs 1:20–33 (ESV)

  • (20) Wisdom cries aloud in the street, in the markets she raises her voice; 

  • (21) at the head of the noisy streets she cries out; at the entrance of the city gates she speaks: 

  • (22) “How long, O simple ones, will you love being simple? How long will scoffers delight in their scoffing and fools hate knowledge? 

  • (23) If you turn at my reproof, behold, I will pour out my spirit to you; I will make my words known to you. 

  • (24) Because I have called and you refused to listen, have stretched out my hand and no one has heeded, 

  • (25) because you have ignored all my counsel and would have none of my reproof, 

  • (26) I also will laugh at your calamity; I will mock when terror strikes you, 

  • (27) when terror strikes you like a storm and your calamity comes like a whirlwind, when distress and anguish come upon you. 

  • (28) Then they will call upon me, but I will not answer; they will seek me diligently but will not find me. 

  • (29) Because they hated knowledge and did not choose the fear of the LORD, 

  • (30) would have none of my counsel and despised all my reproof, 

  • (31) therefore they shall eat the fruit of their way, and have their fill of their own devices. 

  • (32) For the simple are killed by their turning away, and the complacency of fools destroys them; 

  • (33) but whoever listens to me will dwell secure and will be at ease, without dread of disaster.”

B. Sin’s Method: Deceit

Illustration

  • Raise your hand if you think you’re deceived about something?

  • If you know you’re being deceived, you’re not deceived!

The danger of deceit is that deceived people don’t know they are deceived!

Proverbs 16:25 (ESV) — There is a way that seems right to a man, but its end is the way to death.

Physically blind people are always aware of their deficit and spend much of their lives learning to live with its limitations. But the Bible says that we can be spiritually blind and yet think we see quite well. WE even get offended when people act as if they see us better than we see ourselves.

The reality of spiritual blindness has important implications for the Christian community. The Hebrews passage (3:12-14) clearly teaches that personal insight is the product of community. I need you in order to really see and know myself. Otherwise, I will listen to my own arguments, believe my own lies, and buy into my own delusions. My self-perception is as accurate as a carnival mirror. If I am going to see myself clearly, I need you to hold the mirror of God’s Word in front of me. 

— Instruments in the Redeemer’s Hands, p. 54

The devil wants you to believe lies:

  • Lie 1: Sin isn’t that bad

  • Lie 2: There won’t be any consequences

  • Lie 3: No one will find out

  • Lie 4: This sin only affects me

C. Sin’s Goal: Apostasy

Sin wants your heart to be inclined to evil and to “fall away” from God.

The example from the Hebrews in the wilderness

  • Numbers 14:20ff

  • Psalm 95:7-11

Sin can start SO SMALL. (James 3:1-6)

James 3:1–6 (ESV)

  • (1) Not many of you should become teachers, my brothers, for you know that we who teach will be judged with greater strictness. 

  • (2) For we all stumble in many ways. And if anyone does not stumble in what he says, he is a perfect man, able also to bridle his whole body. 

  • (3) If we put bits into the mouths of horses so that they obey us, we guide their whole bodies as well. 

  • (4) Look at the ships also: though they are so large and are driven by strong winds, they are guided by a very small rudder wherever the will of the pilot directs. 

  • (5) So also the tongue is a small member, yet it boasts of great things. How great a forest is set ablaze by such a small fire! 

  • (6) And the tongue is a fire, a world of unrighteousness. The tongue is set among our members, staining the whole body, setting on fire the entire course of life, and set on fire by hell.

II. Exhortation: The “LifeGuard” Warnings of Christian Community

Question: How does a Lifeguard help people?

Why? To prevent sin’s deceit from hardening us.

Who needs this? Believers

Who must give this? Believers

When? Every Day

What is Exhortation?

  • To “call to one’s side”

  • to urge strongly, appeal to, encourage

The word translated exhort (parakleite) is the word of strong encouragement. It is the word of the confident, heartening captain before battle. It is often used in secular Greek literature of the naval or military commander putting strength into his sailors or soldiers. (Raymond Brown, Bible Speaks Today, p. 88)

A. Receiving Exhortation

The more we understand our own hearts, the more we see that it takes a work of God’s grace to transform self-absorbed individuals into a community of love. (How People Change, p. 72)

B. Giving Exhortation

First, as we help restore people to where God wants them to be, we are called to “carry each other’s burdens” (Gal. 6:2). We are also told to fight the deceitfulness of sin by “encouraging one another daily” (Heb 3:13). We must love people enough to do more than expose wrong, pronounce right, and walk away. Accountability requires a willingness to roll up our sleeves and get alongside people as they fight the war between sin and righteousness. (Instruments, p. 268)

How to Exhort others

  • Get the Log Out! — Matthew 7:5

  • Gently and Humbly — Gal 6:1; Prov 15:1

  • Graciously – Prov 12:18; 25:11

  • Truthfully – Eph 4:15

1 Peter 4:8 (ESV) — Above all, keep loving one another earnestly, since love covers a multitude of sins.

It is Unloving and Wrong to Ignore Sin if…

  • the sin creates an unreconciled relationship (Matt. 5:23-24; Phil 2:1-4)

  • you are not confident that the person is growing in the direction of Christlikeness and regularly confessing his sin and working to change. (Heb. 3:12-14; James 5:19-20; 2 Pet 1:5-10)

  • you know (or expect) there will be consequences of this sin that will hurt others in the offender’s life (Matt 18:6; 1 Cor 5:6-7; 12:26)

The more we learn to allow others to speak the Word to us, to accept humbly and gratefully even severe reproaches and admonitions, the more free and objective will we be in speaking ourselves. (Bonhoeffer, Life Together, p. 106)

Discussion Questions

  1. Is there an area of “small” sins that God has revealed in your life?

  2. We are tempted to think we “know our heart” better than others? Why is this dangerous?

  3. What are some ways you can prepare yourself to graciously receive exhortation from others?

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