1 John 4:1-3 (ESV)
Beloved, do not believe every spirit, but test the spirits to see whether they are from God, for many false prophets have gone out into the world.  By this you know the Spirit of God: every spirit that confesses that Jesus Christ has come in the flesh is from God,  and every spirit that does not confess Jesus is not from God. This is the spirit of the antichrist, which you heard was coming and now is in the world already.
It is fitting to talk of spirits and the Holy Spirit in this week of Pentecost. John warns us that there are spirits out there that are not to be believed. Today everyone is “spiritual”. I am always left asking but of what spirit? There are good spirits and bad spirits. The Devil is spiritual. John though is warning the church. John is warning believers not to be led astray by the spirit of the anti-Christ who is in the world already.
John will give two tests to discern the spirits, neither have to do with asking God for a burning bosom. . The first one is recorded here in these three verses. It is this, every spirit that confesses Jesus Christ having come in the flesh is from God. If they do not confess Jesus they are not from God. To confess Jesus Christ has come in the flesh is to preserve the confession as we have it in the four Gospels. It is to confess that he is God and Man, and always has been God. This is in the “has come in the flesh”. It is nothing to believe that there was a man in first century Palestine that was named Jesus and called the Christ. But to confess that Jesus Christ has come in the flesh is to confess that he was in something else before, that he wasn’t always in the flesh. The rest of us were conceived in the flesh and have had no existence outside the flesh. But Jesus Christ had a “pre-existence” if you will. He is the only-begotten Son of God. He is the only one generated and not created by God. The rest of us are children by virtue of creation, and generation of earthly parents. Jesus, the son of God, who refers to the Father, as My Father, was generated. We will never know all the ins and outs of this. Our finite mind is limited in its ability to penetrate the things of God, but must remain bound by His revelation. Jesus Came in the flesh. Jesus rose in the flesh. Jesus will come again in the flesh. He does so in the flesh, so as to redeem us who are of the flesh. If Jesus had not come in the flesh he could not redeem us who are of the flesh. He redeemed all of us, every part of us. He has redeemed us mind, body and soul. And for this we can be thankful.
But those spirits who deny this, they are not from God. They are to be shunned and avoided, not listened to.