Any one of the Bible’s six marks of false prophets is sufficient identification:

• Through signs and wonders they lead astray after false gods (Dt. 13:1-4)
• Their prophecies don’t come to pass (Dt. 18:20-22)
• They contradict God’s Word (Is. 8:20)
• They bear bad fruit (Mt. 7:18-20);
• All men speak well of them (Lk. 6:26)
• They deny that Jesus, the one and only Christ, has come once and for all in the flesh (I Jn. 4:3).

Dave Hunt, quoted in The Berean Call, Bend, Oregon, March 1997, p. 1