The scripture provides a very effective and simple test that anyone can apply to detect false teachers:
Satan is going to come with everything he has but just remember this, the one thing that satan cannot do is to cast himself out of a person:
Matthew 12:26 King James Version (KJV)
26 And if Satan cast out Satan, he is divided against himself; how shall then his kingdom stand?
Beware of the teacher or prophet or evangelist or bishop that preaches but does not demonstrate the spirit and the power:
1 Corinthians 2:4-5 King James Version (KJV)
4 And my speech and my preaching was not with enticing words of man’s wisdom, but in demonstration of the Spirit and of power:
5 That your faith should not stand in the wisdom of men, but in the power of God.