First John 5:20 tells believers that the Son of God has come, has given them understanding, and has joined them to the One who is true, so that they know the true God and possess eternal life. The verse is the closing confession of the letter’s main argument: that real knowledge of God is found in Jesus Christ. The apostle John, traditionally identified as the author of this letter, writes to a congregation of believers he calls his “little children,” reminding them what they already know and why it matters.
We know that the Son of God has come, and has given us an understanding, that we know him who is true, and we are in him who is true, in his Son Jesus Christ. This is the true God, and eternal life.
1 John 5:20 (WEB)
What 1 John 5:20 Means
The verse begins with “We know,” a phrase John uses often in this letter. He is not asking his readers to guess or hope. He is pointing to settled convictions that belong to the community of faith. The first claim is that “the Son of God has come.” This is the core of the Christian message: God did not remain distant but entered human history in Jesus.
Next comes the gift of “an understanding.” The Son has not only arrived; He has opened the mind so that believers can recognize God. The purpose is stated plainly: “that we know him who is true.” Truth here is more than accurate information. It describes the reliable, genuine God who can be trusted, in contrast to the false gods and deceptions John warns against elsewhere.
The verse then describes a close union: believers are “in him who is true, in his Son Jesus Christ.” Being in Christ is a relationship of belonging, not merely agreement with ideas. The closing sentence identifies “the true God” and “eternal life” with each other, so the life believers receive is life with God himself. The verse does not promise ease, comfort, or any particular outcome in this world. It describes what is already true for those who belong to Christ.
The Context of 1 John 5:20
First John is a pastoral letter rather than a formal treatise. It was written to a church or group of churches facing teachers who denied that Jesus had come in the flesh and who claimed special knowledge while living carelessly. John responds by insisting that true knowledge of God always shows itself in faith in Jesus and in love for others. The letter repeatedly contrasts light and darkness, truth and lies, love and hatred, so that its readers can test what they hear.
The verses just before this one describe the believer’s security. Verse 18 says that the one born of God “keeps himself,” and verse 19 says that “the whole world lies in the power of the evil one,” but that believers belong to God. Verse 20 therefore functions as a grounding statement: the reason believers are not captive to the world is that they know the true God through his Son. Verse 21, which immediately follows, warns the readers to “keep yourselves from idols.” Read in this setting, verse 20 is the foundation for that warning. Turning away from idols makes sense only because the true God has been revealed.
Key Phrases in 1 John 5:20
John 17:3
This is eternal life, that they should know you, the only true God, and him whom you sent, Jesus Christ.
(WEB)
In his prayer before the cross, Jesus defines eternal life as knowing the only true God and Jesus Christ whom he sent. The language closely parallels 1 John 5:20, showing that the letter’s teaching rests on the words of Jesus himself. Reading the two together reinforces that eternal life is a knowing relationship rather than a future reward alone.
1 John 4:15
Whoever confesses that Jesus is the Son of God, God remains in him, and he in God.
(WEB)
This verse says that whoever confesses that Jesus is the Son of God, God lives in that person and that person in God. It expresses the same mutual indwelling and the same confession of the Son that appears in 1 John 5:20. Together they show how John connects right belief about Jesus with a real, shared life with God.
A Short Prayer From 1 John 5:20
Lord, thank you that your Son has come into our world and made yourself known to us. We confess that we are not able to understand you on our own, so we ask you to give us the understanding that comes from Jesus. Help us to know you who are true, and to rest in our place within him. When our minds are crowded with other voices and false hopes, draw us back to the truth of who you are. Let the knowledge of you shape how we live today, and keep us from turning to anything that takes your place. Amen.
