Matt 16:6
6 Then Jesus said unto them, Take heed and beware of the leaven of the Pharisees and of the Sadducees.
Mark 8:15
15 And he charged them, saying, Take heed, beware of the leaven of the Pharisees, and of the leaven of Herod.
The leaven of the Pharisees - This leaven expands the philosophy that if you dot every i and cross every t on the outside that you are pleasing God.
This is the leaven of hypocrisy.
The leaven of the Sadducees - This leaven expands the philosophy of questioning and doubting traditionally held views. They refused to acknowledge Oral History or Oral Law.
This is the leaven of compromise.
The leaven of Herod - This leaven expanded the philosophy of tolerance. Herod had to walk a fine line between Roman paganism and Hebraic doctrine to remain in favor with the Roman government. This resulted in a hybrid and convoluted religious culture that embraced worldliness.
This is the leaven of appeasement.
God help us to remove all the leaven from our lives and preach it out of our churches.