So they called these days Purim, after the name Pur. Esther 9:26

To make a long story short, the king gave Esther and Mordecai the estate of Haman. He also gave them permission to make a law for the Jews to protect themselves during Haman’s day of assault.
The Jews overcame their enemies and declared a holiday.

The Jews celebrate Purim on Adar 14 or 15 (Feb/Mar), that these days should be remembered and kept throughout every generation, every family, every province, and every city, that these days of Purim should not fail to be observed among the Jews, and that the memory of them should not perish among their descendants. Esther 9:28

Purim and Hanukkah are not God ordained festival days as those given in the Torah. Yet, these two holidays give generations a reminder of God’s provision for His people.
A Christian has reason to celebrate also.
I could celebrate January 15th as the day I was born-again.
December 7th as the day I was baptized in water.
October 10th as the day CrossRoads Christian Center Church began.
May 4th as the day I God provided my help-meet for life.
And though I do remember and recognized these days, some more than others, I could make remembrance of many more days that I let slip by.
Days of fasting and prayer, in which the Spirit of God came upon me.
Days where a prayer was answered.
Days where someone I know heard the Gospel and accepted Jesus as Savior.
Sooner or later you find yourself celebrating God every day of the year!