Live Brilliantly - A Study In The Book Of 1 John

Day 1 of 10 • This day’s reading


Under God's Microscope


Light both illuminates and exposes darkness. The most common microscope—a light microscope—uses a light source refracted through a system of lenses to magnify small images. It also allows for the examination of dark objects. The book of 1 John is like God's microscope: its message illuminates the authenticity of His children. If you are truly a child of God, then you possess His DNA, and His DNA is light. "God is light and in Him is no darkness at all" (1 John 1:5). 

You Can Be Sure

In 1 John 5:13, John said, "These things I have written to you who believe in the name of the Son of God, that you may know that you have eternal life, and that you may continue to believe in the name of the Son of God." The theme of this epistle is not salvation, rather 1 John provides believers with assurance of their salvation—assurance of eternal life. 

Like John, I want you to know without a doubt that your salvation is secure, and this light microscope of Scripture—1 John—provides three tests that can help you determine whether your eternity is secure, whether you have God's DNA in you. 

The Moral Test: Walking in Light

Light is the litmus test of righteousness. Is His light in you? If so, there will be evidence of obedience in your life. If so, you will be a doer, not just a hearer of God's Word. If so, you will have fellowship with God and with other believers. John called this "[walking] in the light as He is in the light" (1 John 1:7). It's possible to show up at church every Sunday and still have no light shining in you. 

To walk in the light doesn't mean you are sinless, but it does mean that you sin less and less. As you increase your exposure to the light—to the Father, to the Word, to fellow believers—sin will decrease. Of course, we can never be totally free from sin this side of heaven. John wrote that "if we say that we have no sin, we deceive ourselves" (v. 8). 

The Relational Test: Walking in Love

Can you put love under a microscope? John did. In 1 John 3:16, he said, "By this we know love, because He laid down His life for us." How do we know God loves us? Jesus died on the cross for us. But it doesn't end there, as the verse continues, "And we also ought to lay down our lives for the brethren." 

Love in the scriptural sense is an action verb. It's what you do. And the Bible upholds sacrificial love above any other kind of love. Do you love sacrificially, giving your time, your money, your energy, and your attention? Jesus said, "By this all will know that you are My disciples, if you have love for one another" (John 13:35).

When you were born again, you were born into a new family: God's family. And God's DNA is love. First John 4:7 says, "Beloved, let us love one another, for love is of God; and everyone who loves is born of God and knows God." By contrast, John said that if a Christian does not love, then they are not a believer. "If someone says, 'I love God,' and hates his brother, he is a liar; for he who does not love his brother whom he has seen, how can he love God whom he has not seen?" (v. 20).

A.W. Tozer wrote, "From God's other known attributes we may learn much about His love. We can know, for instance, that because God is self-existent, His love had no beginning; because He is eternal, His love can have no end; because He is infinite, it has no limit; because He is holy, it is the quintessence of all spotless purity; because He is immense, His love is an incomprehensibly vast, bottomless, shoreless sea before which we kneel in joyful silence and from which the loftiest eloquence retreats confused and abashed."[1]

The Scriptural Test: Walking in Truth

John spoke repeatedly about walking in truth. When he wrote 1 John, a false doctrine known as Gnosticism had risen in the early church and was distorting the gospel. In that atmosphere, John reminded the early believers—and us—of four nonnegotiable truths of Christianity. 

Truth One: Jesus is the preexistent Son of God. Truth Two: Jesus is the second person of the Trinity. He is deity, the God-man. Truth Three: Jesus was God who became flesh at a fixed point in time in history. Truth Four: Jesus' death cleanses us of our sins.

John responded to the dangerous rise of false doctrine with biblical truth. He knew the early church needed sound doctrine—and so do we.


The FBI examines money under a microscope, diligently searching for counterfeit currency. But they don't study counterfeit notes to be able to tell what the real thing is; they study the real thing itself, the truth. In the same way, 1 John provides assurance of salvation by placing light, love, and truth under a microscope. "By this we know that we are of the truth, and shall assure our hearts before Him" (1 John 3:19). If you walk in light, you pass the moral test. If you walk in love, you pass the relational test. If you walk in truth, you pass the scriptural test. Then you can be sure that your salvation is secure. 


Lord, You are light and love. Your Word is true. As I study 1 John, help me to place my own life under the microscope of Scripture, knowing that You want to increase Your light and decrease sin in me. Please forgive me and help me to walk in light, love, and truth. God, I want to live brilliantly for You. In Jesus' name, amen.