I think that the events in the Scroll of Esther teach a variety of lessons about identity, heritage and faith but possibly the simplest and most powerful lesson may have nothing to do with the acclaimed actions of the heroes.
While Esther's bravery might teach us of the power of a woman's will and character, the scroll includes a more telling anecdote regarding another couple and an insight a woman has which her husband can't see. Haman (boooooo), in chapter 6, sees that he must honor Mordechai the Jew whom he has conspired to kill. He is annoyed and vents to his wife Zeresh. Her answer? "If Mordechai is of the Jewish people, you will fail in your machinations against him." Haman knew that Mordechai was Jewish way back when, in chapter 3! Why didn't Zeresh warn him then that there was this accepted wisdom about plans against Jews not working out? In fact, just the opposite occurs! In. Chapter 5, when Haman vents to his wife and wise friends about Mordechai's not bowing to Haman, and he identifies Mordchai as a Jew, they are the ones who suggest the gallows! So why would Zeresh choose only later to quote the notion that a plan against Jews won't work? What happened in the interim?
There was a subtle but major shift between the two conversations between Haman and Zeresh - the king in chapter 6 had discovered Mordechai's heroic but downplayed behavior from chapter 2 and saw that it had to be rewarded; this is what Haman recounted. Zeresh recognized that Mordechai was not a Jew in name only! Haman could not see the distinction between lineage and personal behavior. This is why Zeresh says "if Mordechai is of the seed of the Jews." This contrasts with Haman's statement that Mordechai simply is a Jew.
Zeresh had an insight into our position as Jews. She understood that it isn't about calling outselves "Jews" which will guarantee any divine aid, but our righteous actions which firmly place us in the chain forged by generations of Jews stepping up and acting like Jews.
This Purim, let's adopt Zeresh's clear perception and step up to act like Jews as part of zera Yehudim, instead of simply applying a label of Jew to ourselves and ignoring the responsibilities which come along with it.