God has always encouraged his people to think critically about the content of the teaching they hear. Twice in Deuteronomy (13:1-5; 18:22) and again in Jeremiah (28:9), tests are provided the verify the authenticity of the prophetic message. Jesus addressed this as well in the Sermon on the Mount (Matthew 7:16-20) with the challenge, “You shall know them by their fruit.” The first century was filled with itinerant teachers. Like Paul and the apostles, itinerant teachers would travel from community to community, sharing their inspired messages about God. Some who went out were legitimate, spreading the gospel and starting churches. Others were illegitimate. Itinerant teachers had no source of income other than the hospitality of the listeners. The illegitimate teachers would seek to share messages that would allow them to profit. You don’t have to be an economics major to understand that the bigger the audience, the bigger the income potential. So the false teachers would tailor their messages to have a broad base of appeal so they could profit from the people. Evidently, John’s readers tended to accept any and all teaching that claimed to be inspired. John’s pastoral response to this trend was to challenge them to investigate the source of every claim.
Dear friends, do not believe everyone who claims to speak by the Spirit. You must test them to see if the spirit they have comes from God. For there are many false prophets in the world. This is how we know if they have the Spirit of God: If a person claiming to be a propheta acknowledges that Jesus Christ came in a real body, that person has the Spirit of God. But if someone claims to be a prophet and does not acknowledge the truth about Jesus, that person is not from God. Such a person has the spirit of the Antichrist, which you heard is coming into the world and indeed is already here. But you belong to God, my dear children. You have already won a victory over those people, because the Spirit who lives in you is greater than the spirit who lives in the world. Those people belong to this world, so they speak from the world’s viewpoint, and the world listens to them. But we belong to God, and those who know God listen to us. If they do not belong to God, they do not listen to us. That is how we know if someone has the Spirit of truth or the spirit of deception” (1 John 4:1-6, NLT).
John’s counsel to the church was two fold: examine the teacher’s message in light of Jesus Christ; and to test the audience to see if the message is gaining popular appeal from the world. Times have changed over 2,000 years. Their historical setting is not exactly like ours today, and we face the same dangers in different ways. Like then, there is a lot of static in the signal. Things are different today but the overarching principle that remains. Everything we hear or read must be filtered through the lens of Jesus Christ. He is the standard.