How does Nathaniel Hawthorne's moral, "Be true, be true, be true" apply to the novel?

Well you really have to be true to who you are. Most of the Puritans lived their life in fear. They had a strict script which they had to adhere to at all costs. They had to look and act pious all the time. Hester, Pearl and Dimmesdale had something real going on. Hester had to wear the shame of her love and Dimmesdale got sick hiding behind a lie. Pearl was probably the most guilt free soul there. It isn't until the end of the novel when Dimmesdale is finally true to himself and his God. He mounts the scaffold with Hester and Pearl. He tells the world, or at least the village, the truth. Hester too feels this rush of pride. The truth really does set these people free. It exists under the weight of sanctimonious lies that the Puritans used to validate themselves to each other.