The climax has come, and Haman, the enemy of the Jews is dead (Esther 7:10). While Esther is not out of the woods just yet, the worst is over.
Ahasuerus had given Haman his royal signet, and Haman had used it to draw up a decree which could not be revoked: to kill all the Jews. When Esther throws herself at the feet of the king on behalf of her people, asking him to revoke it, the king points out to her that he has just killed her enemy and given her power. She is now able to use that power to save her people. Now that Mordecai has the royal signet (8:2), he is able to make a new edict. Mordecai issues a counter edict.
If we look at Esther 8:1-15 and compare it with Esther 3:10-4:1, we see that the new edict is mirrored by the old one, this time in favour of the Jews. As we look at the similarities, we can see that this is a total reversal; from death to life.
As we make the connection between Esther and our own time, we can see that God, through Christ, issued his own counter-decree. We are born under a decree of death (Rom. 6:23). In Adam, we are all born into sin (I Cor. 15:22). God's counter decree in Christ provides victory: from sin and death to life. As through one man's transgression sin entered the world, through one man, Jesus Christ, the price for sin is paid. Complete reversal.
The counter-decree that Mordecai issued comes after a series of complicated events which only God could have orchestrated. Esther "just happened" to have been in the palace when the threat came upon the Jews. Mordecai "just happened" to hear a plot against Ahasuerus, and was able to save him. The king "just happened" to have a sleepless night which led to him discovering what Mordecai did. The list of "just happened" goes on and on. Looking at those moments, we see the handiwork of a sovereign God.
Perhaps we could question Mordecai's wisdom when he suggested that Esther keep her Jewishness a secret. Perhaps we could question his wisdom in refusing to bow to Haman, which was what ultimately set the death decree in motion. Perhaps it would have avoided the death decree of Haman completely. Perhaps God wanted it exactly this way, so he could set in motion a reversal that draws our minds and hearts to the reversal that Christ provides for us through his shed blood.
Even if you don't believe in God, the book of Esther is a masterful work of literature. However, I do believe in God, and I believe in the innerancy and inspiration of Scripture, and seeing how God uses his word continues to amaze me, and leave me in awe.