The notion of Herod’s leaven, referring to pervading harmful influence, appears only once in the New Testament (Mark 8:15).
Yeshua, the Son of God, cautioned His close disciples in a sharp warning to watch out not only for the leaven of Herod, but also to beware of two other “leavens”: of the Pharisees and of the Sadducees (Matt. 16:6, 11-12).
In this context, the leaven in the words of the Lord Yeshua points to different kinds of distortion and wickedness which rapidly spread in society. And remember, leaven, or yeast, causes dough to ferment and rise quickly.
When speaking about the three kinds of leaven – of Herod, of the Pharisees and of the Sadducees – the Lord did not specify the distinctive traits of each and every kind of “leaven.” However, one can easily imagine that the leaven of the three parties represent three poisonous wrongs, being three destructive ways of thought and conduct. While they characterize three different directions, they still overlap in certain spheres.