What is Book of Esther's purpose?

As a Christian, how should I understand the book of Esther? Meaning, what does it tell me, and what should I take from it to make me a better Christians, or even not to make me a better Christian what should I take from it? Does the book of Esther itself give any direction that would help Christians? Or maybe, as quoted from this answer? >Anyway, Esther is in the Christian Bible because it is in the Jewish Bible. Why would the Jews include it in their Bible? Chiefly because it tells the story for one of their feasts, that of Purim. Purim is a joyous festival in which they act out the story of Esther by reading through the book of Esther.