The First Letter of John seems to have been written to oppose a certain movement that had sprung up within the early church. Many of the letters we have read thus far contain teachings on very specific issues which are being faced by the recipient church. In this case, John seems to be trying to head off this movement before it is able to sweep through the church. As more and more people were hearing about the Gospel, many of the new believers had trouble understanding Jesus. Was he a prophet or a king? Was he really a human or a spirit disguise as a human? How could he be fully God and yet suffer and die?
One idea became very popular in the early church to understand Jesus. This was called Docetism and it was a belief that Jesus Christ was a spirit, not a physical human being but merely appeared to have human form. The name reflects this belief as the Greek word ‘dokeo’ means to seem. However, John is writing to remind believers that this is not true. Many who taught this way of thinking would claim to have been inspired by the Holy Spirit and so John says, “Dear friends, do not believe every spirit, but test the spirits to see whether they are from God, because many false prophets have gone out into the world. 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.” 1 John 4:1-3