There is something scary in John’s words that we are to test the spirits. After all, Jesus warns us to not attribute works of the Holy Spirit to the devil. If we do, we can never be forgiven. But Jesus’ warning is just the point of John. John is referring to people claiming to speak by the Spirit. There are many voices out there calling for our attention, claiming to be the truth. We need to discern which voices are from God and which are from the world. We are to know and follow only the voice of Jesus. Yes, we need to be very careful and do this together with other followers of Christ.
This isn’t always easy. John gives us a key, “This is how you can recognize the Spirit of God: Every spirit that acknowledges that Jesus Christ has come in the flesh is from God, but every spirit that does not acknowledge Jesus is not from God.” Now that seems to be very specific, and not all voices will even make an indication of what their position is. It is but one key. John says the voice must teach that Jesus is real, that he is the person as presented in the New Testament. If we start there we eliminate a lot of false teaching.
The true voice speaks the words of Christ calling us to live like Christ. The voice who serves the living Jesus and proclaims Him and all that He is, that voice should be our voice. We need to listen to Paul’s instruction to test ourselves and in doing so we will be able to better test other voices. What if we acknowledge Jesus as real? We will be able to lead others to Christ and eternal life.
For God loved the world in this way: He gave His One and Only Son, so that everyone who believes in Him will not perish but have eternal life. -John 3:16 HCSB