Then they understood that he had not told them to beware of the yeast of bread but of the teaching of the Pharisees and Sadducees.
For I tell you, unless your righteousness exceeds that of the scribes and Pharisees, you will never enter the kingdom of heaven.
(The Sadducees say that there is no resurrection or angel or spirit, but the Pharisees acknowledge all three.)
But when he saw many of the Pharisees and Sadducees coming for his baptism, he said to them, “You brood of vipers! Who warned you to flee from the coming wrath?
How could you fail to perceive that I was not speaking about bread? Beware of the yeast of the Pharisees and Sadducees!”
Your boasting is not a good thing. Do you not know that a little yeast leavens all of the dough?