“We are of God. He who knows God hears us; he who is not of God does not hear us. By this we know the spirit of truth and the spirit of error.” (1 Jn. 4:6) John says to first century Christians that they could tell who their friends should be based on who they listen to. People who hear the apostles know God.
John is paraphrasing what Jesus had told the Jews in John 8: “Why do you not understand My speech? Because you are not able to listen to my word. You are of your father the devil, and the desires of your father you want to do… He who is of God hears God’s words; therefore you do not hear, because you are not of God.” (Jn. 8:43-44, 47)
Throughout the history of the world there is this fundamental divide, and it runs through nations, families, communities, and even churches. We preach the covenant, we preach the objective claim of God upon every baptized individual: you belong to Jesus. But we insist with Jesus and John and all the apostles: you must know God. God must be your Father. You must hear His words, love His words, feed on His words, grow up into His words.
This naturally creates communities and friendships of love on the one hand, fellowship based in Jesus, and on the other hand communities and friendships based on fear, insecurity, and bitterness. So who are you? Are you of God? Or is the Bible just a lot of words? Is the word of God like honey to your soul? Or are you just memorizing little snippets of words so you can try to fit in? Whose word is your confidence? Your courage? Your strength?
One of the key ways we prove that we understand Jesus and His words is by confessing our sins, by agreeing with God about our sin, that Jesus did in fact need to suffer and die to make us clean and right.