A.T. Robertson Commentary Matthew 7:15

"Beware of false prophets, who come to you in sheep`s clothing, but inwardly are ravening wolves." — Matthew 7:15 (ASV)

False prophets (των ψευδοπροφητων). There were false prophets in the time of the Old Testament prophets. Jesus will predict "false Messiahs and false prophets" (Matthew 24:24) who will lead many astray. They came in due time posing as angels of light like Satan, Judaizers (2 Corinthians 11:13f..) and Gnostics (1 John 4:1; 1 Timothy 4:1). Already false prophets were on hand when Jesus spoke on this occasion (cf. Acts 13:6; 2 Peter 2:1). In outward appearance they look like sheep in the sheep's clothing which they wear, but within they are "ravening wolves" (λυκο αρπαγες), greedy for power, gain, self. It is a tragedy that such men and women reappear through the ages and always find victims. Wolves are more dangerous than dogs and hogs.