He very cunningly denied that Jesus Christ was true God. He was finally found out and deposed from office. They are of Satan who is very cunning. St. Paul says at II Cor. For Satan himself transforms himself into an angel of light.
False teachers are Satanic in their deception.
Think of how Satan, the false teacher, deceived our first parents in Gen. 3. Think of how Satan tried to deceive Job and his friends. God permitted Satan to test Job. His friends interpreted that trial as caused by unrepented sin in Job. 16-20 A. Christians can distinguish these works and fruits.