"Beloved, 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.  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; and this is the spirit of the antichrist, of which you have heard that it is coming, and now it is already in the world."

John understands that there is a difference between a believer in God and a follower of God.  A believer of God is changed by the encounter with God.  A follower of God is constantly growing toward the character of God - consistently looking more like Christ.

This is why John asks us to test every spirit.  It is so easy for us to follow our own will and believe whatever feels right. John insists that there is only ONE right - it is the spirit that confesses Jesus has come to earth.

If you seek righteousness - seek Truth.