The Best way to spot an imposter is to be familiar with the real thing.
2 John 7-10
For many deceivers are entered into the world, who confess not that Jesus Christ is come in the flesh. This is a deceiver and an antichrist. Look to yourselves, that we lose not those things which we have wrought, but that we receive a full reward. Whosoever transgresseth, and abideth not in the doctrine of Christ, hath not God. He that abideth in the doctrine of Christ, he hath both the Father and the Son. If there come any unto you, and bring not this doctrine, receive him not into your house, neither bid him God speed: