Thanks for asking about this passage from the Gospel of Luke (12:1-3): "Beware of the leaven of the Pharisees, which is hypocrisy. Nothing is covered up that will not be revealed, or hidden that will not be known. Therefore whatever you have said in the dark shall be heard in the light, and what you have whispered in private rooms shall be proclaimed upon the housetops" (RSV).
Jesus frequently uses "leaven" as a symbol for the choices we make about what we believe, about God and about ourselves. On the one hand "the kingdom of heaven is like leaven" (Mt. 13:33). This suggests that choosing to believe in the Christ, the spiritual Presence and Power that is our true identity, acts on all the elements of our lives, just as leaven acts on the ingredients with which it’s mixed, and the result is a life experience that is enlivened and energized into the expression of the Christ that Jesus describes as the kingdom of heaven. On the other hand, his followers are told in this passage to "beware the leaven of the Pharisees, which is hypocrisy." By choosing to believe in the energy of limitation, judgment and blind obedience that the Pharisees demanded, our lives become expressions of those same negative energies. The elements of a life experience may be the same—the same relationships, the same challenges—but the result will be dramatically different depending on the "leaven" we choose to add to the mix—a positive leaven of love or a negative leaven of fear.
And this power we have of creating our own consciousness according to what we choose to believe cannot be accomplished in secret. Hypocrisy comes from the Greek for "actor," and it suggests that the Pharisees try to put up a false front that hides the inherent negativity of their beliefs. Jesus insists often that it won’t work —the beliefs we try to hide within will express openly in our lives, whether we intend it or not. Negative beliefs will express negatively; positive beliefs will express positively, according to the unshakeable Law of Mind Action. We may think we’re keeping secrets; but in fact those secrets are expressing throughout our lives.
I hope this helps you understand the guidance that led you to this passage.