We Can Know: What 1 John 5 Teaches About Assurance

We reach the final chapter of John’s First Epistle. Our series has been called “Light, Love and Life Through Jesus.”

In the previous chapter, John shared two important truths we can hold onto: (1) We must test every teaching and its source to discern its credibility or falsehood. And (2) loving one another is the sign that we truly know God. As John said in 4:8, “Anyone who does not love does not know God, because God is love.” And again in 4:21, “Whoever loves God must also love his brother.” Loving God and loving His people: it’s a package deal.

Now as we come to this final chapter, John closes with encouragement. He gives us assurance. Assurance of the victory we have in Christ. Assurance of the testimony God has given us. And assurance of the eternal life we share in His Son.

There’s a lot we can be sure of. A lot more than many Christians realize.

They say that “talk is cheap.” And so it is. The world is full of empty promises and false hope. Broken contracts. Broken homes. Broken people. So when John speaks of God’s promises, he assures us that we’re dealing with the character and integrity of God Himself.

We Can Conquer the Cosmos: Rise Above the World (vs 1-5)

Read 1 John 5:1-5 (ESV)

Three times John says “overcome the world” in verses 4-5. The Greek word nikao means conquer. Kosmos means the world. Put together: we’ve conquered the cosmos. Not someday in the future, but right now. We are overcoming the world in an ongoing reality.

If we allow it, the world can overwhelm us. Swim in cable news or scroll social media long enough, you’ll come away convinced we’re hopeless. But this world is temporary. The kingdoms of this world will end. Don’t put your faith in the world or any part of it.

Discussion

Verses 4 and 5 tell us WHO has conquered the cosmos. Who is it? (“Everyone born of God.” That’s you, if you’re in Christ. If you have been born again, you have already overcome.)
How do we overcome the world? How do we conquer the cosmos? (Three things: Faith in Jesus, because faith in Christ is the victory. Love, because love for the Father produces obedience naturally, and His commandments are not burdensome. And obedience, because to love God and keep His commands is to love His people.)
Where do faith, love, and obedience spring from? (Not willpower, but a new life. John keeps saying “born of God.” To someone outside Christ, His commands might feel heavy. To the one born of God, obedience is natural. It’s freedom, not a burden.)

Key Takeaways

Faith is the victory. Not our effort, but trusting in Jesus.
Love proves itself. Loving God means loving His people.
Obedience is freedom. His commands aren’t a burden when we’re born of God.

We Can Trust God’s Testimony: Reflect on His Word (vs 6-12)

Read 1 John 5:6-12 (ESV)

John uses the word testify and testimony over and over in this passage. It’s courtroom language. God said, “This is my Beloved Son, in whom I am well pleased.” What greater endorsement is there? He says “the testimony of God is greater” than the testimony of men (v. 9). Don’t take John’s word for it. God Himself bears witness.

Who are the three witnesses John describes in verses 7-8? Water, blood, and Spirit. Water points to Christ’s baptism, at the start of His ministry. Blood points to the cross, where He said, “It is finished.” The Spirit is God’s ongoing witness, who descended like a dove at His baptism and was sent in power like a mighty rushing wind at Pentecost. Together, they point to the whole truth of Jesus’ identity.

John says in verse 12, “Whoever has the Son has life.” To belong to Christ. Eternal life isn’t something we wait to earn. When we have Him, we have eternal life already.

And what does it mean to “have” the testimony in us (v. 10)? Having the testimony in us simply means we can add our voice to the chorus of witnesses: the Father, the water, the blood, and the Spirit. Because we too have encountered Him.

Discussion

Why do you think John piles up the word “testimony” here instead of just saying, “Trust me”?
Who are the three witnesses John describes in verses 7-8? What do they point to?
John says in verse 12, “Whoever has the Son has life.” What does he mean by this?
What does it mean to “have” the testimony in us (v. 10)?

Key Takeaways

God Himself testifies about Jesus. Rejecting the Son is calling God a false witness.
The witnesses agree. Water, blood, and Spirit all confirm His true identity.
Life is in the Son. To have Him is to have eternal life already.
We, too, bear witness because we’ve encountered Him.

We Can Live with Confidence: Rest in His Promises (vs 13-21)

Read 1 John 5:13-21 (ESV)

John plainly states his purpose: “that you may know you have eternal life.” We can know. We can be secure. If we’ve been born of God, we belong to Him.

This confidence extends to prayer. God hears when we ask according to His will (vs. 14-15). We can know this as well. So bring your petitions to Him. He is listening.

Then John addresses sin. Sin “that does not lead to death” and sin that “does” in verses 16-17.

What is sin that leads to death? Three things. Rejecting Christ’s nature: John calls this the spirit of the antichrist. Rejecting God’s will: the persistent practice of lawlessness reveals we do not “have the Son.” Rejecting God’s people: refusing to love our brothers and sisters, which John has hammered all through this letter.

What is a sin that does not lead to death? Stumbling in the frailty of our flesh. We are imperfect. Even when we trust Christ, want His will, and love His people, we still mess up. These are the sins to pray for. But important note: our prayers are for the family of God. The world needs regeneration, not behavior modification. The cosmos, its culture and systems, are irredeemable apart from Jesus. Without Him, there is no hope. With Him, there is life.

What more can we know from verses 18-20? God protects us, even if we stumble. We know we are from God. And best of all, we can know Him. He is eternal life. If we have Him, we will live forever.

And notice how this ends the letter: “Keep yourselves from idols.” The end. Putting our hope in personalities, rituals, the world, or anything in the world is from the enemy.

Discussion

What is sin that leads to death? What is sin that does not lead to death? How do we tell the difference?
What can we know from verses 18-20?
Why does John end the entire letter with “Keep yourselves from idols”? What does that include?

Key Takeaways

We can know. Eternal life is secure in Christ, no guesswork.
We can pray for each other, and put regeneration first before rehabilitation.
We must stay guarded. Keep from idols, anything that steals hope from Christ.

Something to Sit With

Three things John wants us to know from Chapter 5:

We can conquer the cosmos. Rise above the world by faith, love, and obedience.
We can trust God’s testimony. Reflect on His Word, and add your voice to the chorus of witnesses.
We can live with confidence. Rest in His promises. Your eternal life is secure in Him.

John closes this letter not with uncertainty but with assurance. He wants us to walk away with confidence: confidence in our victory through Christ, confidence in God’s testimony, and confidence in the eternal life we already share in Him.

These are not lofty ideals but everyday realities for those born of God. They steady us when the world feels heavy and remind us where our hope truly rests.

Am I living as though faith in Jesus has already given me victory? Or am I still letting the world define me?
Do I take God at His word about His Son? And does my life bear witness alongside His?
Do I rest secure in Christ and pray with boldness? Or do I let doubt and idols steal my assurance?

Rise above the world. Reflect on His Word. And rest in His promises.

“I write these things to you who believe in the name of the Son of God, that you may know that you have eternal life.” (1 John 5:13, ESV)

Frequently Asked Questions

What does it mean to “overcome the world” in 1 John 5?

Overcoming the world means that faith in Christ gives victory over the world’s pressure to conform, compromise, and chase what fades. It is not about escaping the world but about living above its grip. The victory is already won through Christ, and believers experience it now through faith, love, and obedience.

What are the three witnesses in 1 John 5:6-8?

The three witnesses are the Spirit, the water, and the blood. The water points to Jesus’ baptism and public identification as the Son of God. The blood points to the cross and his sacrificial death. The Spirit is the ongoing witness who testifies to the truth of who Jesus is. All three agree and confirm God’s testimony about his Son.

What is the “sin that leads to death” in 1 John 5:16?

In the context of 1 John, sin that leads to death refers to the settled rejection of Jesus as the Christ, the persistent practice of lawlessness that reveals a person does not truly “have the Son,” and the refusal to love the brothers and sisters in the faith. It is not a single failure but a definitive trajectory of unbelief and departure.

How can I have confidence in prayer according to 1 John 5?

John teaches that confidence in prayer comes from aligning with God’s will. “If we ask anything according to his will he hears us.” This is not a blank check but a relationship-shaped confidence. As believers grow in knowing God and his purposes, prayer becomes less about getting what we want and more about joining what God is doing.

What does “keep yourselves from idols” mean at the end of 1 John?

John’s closing warning is not about literal statues. An idol is anything that takes the place of Christ as the source of hope, identity, or security. It could be a personality, a ritual, or any part of the world’s system. The call is to guard the heart and keep Christ in his rightful place as the center of everything.

This lesson is part of the Light, Love and Life Through Jesus series.