They may be men who hold positions of religious leadership. They may well have graduated from a divinity school. Indeed, they might even be seminary professors. Judging on the basis of external indications we might wrongly assume them to be reliable guides, but we must not evaluate them on such external evidence. These false prophets can be detected by their fruits .
Good trees produce good fruit, and rotten trees, bad fruit.
One must be very careful here, for false prophets are not without religious activities. A false prophet is often accompanied by deceptive signs and by seeming wonders. We should expect them to perform deeds which suggest miraculous power. And we should expect that these deeds be performed under the pretext of being done by God's power and to His glory. For such men are false apostles, deceitful workers, disguising themselves as apostles of Christ.