The essence of the Purim story is the concept of ונהפוך הוא, that is, the turning-around aspect of the story in that the opposite of what seems to be happening occurs.
it was turned to the contrary, that the Jews had rule over them that hated them;(9:1)
Haman prepares a gallows but he is hanged upon it. He presumes he is to be honored by the King but must himself so honor Mordechai. Mass murder is planned for the Jews but their enemies are attacked and killed.
The drama begins with the convincing by Haman of King Achasverus to permit him to deal with the Jews, saying:
There is a certain people scattered abroad and dispersed among the peoples in all the provinces of thy kingdom; and their laws are diverse from those of every people; neither keep they the king's laws; therefore it profiteth not the king to suffer them. (3:8)
But what are those "king's laws"?
If we search through the Book of Esther for the term דת we will discover the following "laws":
1:8 And the drinking was according to the law;
That would be public licentiousness
1:10 he commanded...To bring Vashti the queen before the king
That would be sexual harrassment
1:19 If it please the king, let there go a royal commandment from him...That Vashti come no more before king Ahasuerus; and let the king give her royal estate unto another that is better than she.
Indiscriminate execution and property expropriation.
1:20 And when the king’s decree which he shall make shall be published throughout all his empire, (for it is great,) all the wives shall give to their husbands honour, both to great and small.
Oppression of women.
2:2 Then said the king's servants that ministered unto him: 'Let there be sought for the king young virgins fair to look on; and let the king appoint officers in all the provinces of his kingdom, that they may gather together all the fair young virgins unto Shushan the castle,
Kidnapping and forced prostitution.
4:11 All the king’s servants, and the people of the king’s provinces, do know, that whosoever, whether man or woman, shall come unto the king into the inner court, who is not called, there is one law of his to put him to death, except such to whom the king shall hold out the golden sceptre,
Government isolation and lack of interaction with the populace.
For all intents and purposes, these are the characteristics of all tyrannies until this day.
The Jewish religious and cultural heritage is the exact opposite of those "laws" and that is the true message of the story of the Jews in Persia: indeed, we are different and demand the right to be different and our difference will have a positive effect on society.