http://apologeticspress.org/AllegedDiscrepancies.aspx?article=89&b=Esther
Questions and Answers: Why is the Book of Esther in the Bible?
by Kyle Butt, M.Div.
Q.
Why is the book of Esther in the Bible, since it does not mention God? (cf. Wells).
A.
God operates in many different ways. In the book of Exodus, for example, we read about God working through Moses to part the Red Sea, and to turn a shepherd’s rod into a serpent. During New Testament times, God gave Jesus power to heal all manner of sickness, cure blindness, and even raise the dead.
But miracles were only one way in which God worked. He also worked (and continues to work) through providence, which means that He uses natural laws to accomplish His varied purposes. For instance, in Acts 14:17, the apostle Paul explained to his listeners that God gave them “rain from heaven and fruitful seasons,” thereby filling their hearts “with food and gladness.” How had God given them such blessings? Did He miraculously drop apples out of the sky or turn stones to bread? No, He used the natural forces of this world to accomplish His purposes. God always is at work “behind the scenes” to make sure that His ultimate will is accomplished.
When we study the book of Esther, it is true that we never read God’s name. But many of the things that occurred in the book could not have been “just luck.” Take, for instance, the time that King Ahasuerus could not sleep, and his servant “just happened” to read the records of the time that Mordecai had saved the king’s life (Esther 6:1-3). In fact, the entire book of Esther shows that God’s guiding hand was working behind the scenes to save the Jewish nation. Esther’s guardian, Mordecai, once said to her: “Who knows whether you have come to the kingdom for such a time as this?” (Esther 4:14). His statement shows that he was seeing God’s possible plan for Esther.
Today, no person has been given the power to raise the dead or turn sticks into snakes, but God still is at work through His guiding hand of providence. The book of Esther serves to remind us that we do not need to see God (or even read His name) to know that He is “not far from each one of us” (Acts 17:27).
REFERENCE
Wells, Steve, "Esther for Skeptics," http://www.skepticsannotatedbible.com/est/intro.html.