And by this we know that we have come to know him, if we keep his commandments. – 1 John 2:3
Profession of a having a relationship with God cries for proof. It begs for evidence. Following up with his assessment of false claims of intimacy with God found in the previous verses, John says, “Whoever says ‘I know him’ but does not keep his commandments is a liar, and the truth is not in him” (1 John 2:4 ESV). That sounds eerily similar to what John wrote just a few verses earlier. “If we say we have fellowship with him while we walk in darkness, we lie and do not practice the truth” (1 John 1:6 ESV). From John's perspective, the assertion of intimacy with God means nothing without the kind of behavior that gives evidence that one is truly walking in the light. Obedience to the commands of God is proof that one has a relationship with Him through His Son, Jesus Christ the righteous. His light has illuminated the darkness of our lives, exposing the sin within, and replacing it with the power to live holy lives, set apart for His glory. To claim to have an abiding, ongoing, personal and intimate relationship with God through Christ is one thing. To live like it is another. “Whoever says he abides in him ought to walk in the same way in which he walked” (1 John 2:6 ESV). That is a serious and sobering statement. It is a call to a radical, revolutionary kind of lifestyle that looks nothing like what we see modeled on this earth.
Jesus came to dispel darkness. He came to penetrate the darkness of man's sin with the light of His life. He said of Himself, “I am the light of the world. Whoever follows me will not walk in darkness, but will have the light of life” (John 8:12 ESV). But it does no good to claim to know the light of the world if our lives do not reflect the presence of that light on a daily basis and in practical ways. The apostle Paul puts this in terms we can understand and apply. “For God, who said, ‘Let there be light in the darkness,’ has made this light shine in our hearts so we could know the glory of God that is seen in the face of Jesus Christ. We now have this light shining in our hearts, but we ourselves are like fragile clay jars containing this great treasure. This makes it clear that our great power is from God, not from ourselves” (2 Corinthians 4:6-7 NLT). The light of God in the form of His Son, Jesus Christ, has penetrated the darkness of our lives and the result should be that it shine OUT of our lives in ways that prove its existence. John tells us what that should look like on a daily basis. And he ties it back to the greatest commandment as Jesus explained it. “You shall love the Lord your God with all your heart and with all your soul and with all your mind. This is the great and first commandment. And a second is like it: You shall love your neighbor as yourself” (Matthew 22:36-39 ESV). Love God and love others. You can't do one without the other. Without God's help, loving others is impossible. At least, to love them on God's terms is impossible. But it is impossible to say you love God if you can't bring yourself to love those who are supposed to be your brothers and sisters in Christ. Supposedly the darkness of our lives has been penetrated by the light of Christ. But “whoever says he is in the light and hates his brother is still in darkness” (1 John 2:9 ESV). In other words, their behavior does not reflect their so-called relationship with Christ. If anything it contradicts the truth as expressed by Christ Himself. He said, “If you follow me, you won’t have to walk in darkness, because you will have the light that leads to life” (John 8:12 NLT).
To continue to walk (conduct your life) in the dark when you have been exposed to the Light makes no sense. Anyone whose life is marked by hatred rather than love for his brother, is stumbling around in the dark, “because the darkness has blinded his eyes” (1 John 2:11 ESV). But John says, we can know that we have come to know Christ. We can know we have a relationship with God. We can know that we are in him. And the proof is in the transforming power of Christ in us. We can love others. And when we love others we are expressing and proving our love for God. We are giving evidence of His Spirit's presence within us. We are walking (living our lives) in the same way Jesus did. In obedience and dependence upon God. Claiming to know Him is one thing. Living as if we know Him is another. And the strength to accomplish is God-provided, not self-made. “By his divine power, God has given us everything we need for living a godly life” (2 Peter 1:3 NLT). Life transformation is evidence of our ongoing sanctification by God. By this we know.