Matthew 16:5

And the disciples came to the other side and forgot to take bread. And Jesus said unto them, Take heed and beware of the leaven of the Pharisees and Sadducees.

Christ and the apostles re-crossed Lake Galilee to the vicinity of Bethabara-Julius, where, in temporary safety from the Pharisees, he could continue to instruct the Twelve. Christ's warning of the "leaven of the Pharisees and Sadducees" was necessary. They had formed a powerful, socially prominent, politically dominating alliance against him and were advocating his rejection with every cunning and lying argument possible. They argued: (1) that Christ could not be the Messiah, because Elijah had not yet come; (2) that his signs were not "from heaven," but from earth; (3) that the demons he exorcised were, in truth, cast out by the power of the devil; (4) that he was a violator of sacred traditions; (5) that he profaned the sabbath; (6) that the Scriptures "proved" the Messiah could not come from Galilee, but from Bethlehem (John 7:41); (7) that none of the rulers of the people believed on him (John 7:48); (8) that they KNEW him to be a sinner (John 9:24); (9) that he was a glutton and a winebibber; (10) that he was a Samaritan; (11) that he was a friend of publicans and sinners; and (12) that he was a deceiver. (For more on this and for Scripture references on the Pharisees' charges, see under Matthew 11:18,19). Considering WHO THEY WERE, one must allow that they had indeed mounted a formidable attack against the Christ, so strong in fact that Christ saw fit in this instance to warn even the apostles against it.

"Leaven" in this case stands for something evil, the usual meaning in Scriptures, although an exception exists (Matthew 13:33). The Sadducees were materialists, denying any spiritual life, any possibility of a resurrection (Matthew 22:23), and the existence of angels. The Pharisees were hypocrites, dealing in falsehood. Both were secular, dominated by earthly considerations exclusively. They were full of snobbery and pride and made every possible appeal to selfishness, prejudice, and bias. They even tortured the Scriptures to invent arguments against him; and, finally, they relied upon force to achieve their ends. Even at that moment, they were plotting to kill Christ. No group of leaders in human history ever surpassed their right to be denominated as "the sons of the evil one."