Rabbi Noson Weisz explains the spiritual input that God offers on Purim:
There is much more to Judaism than the outer trappings of observance. Observance is the body of Judaism, but its soul requires the Jews to place their relationship with God at the very center of life. The observance of the commandments is only meaningful when it is the outer manifestation of this inner reality. One cannot be truly Jewish without dreaming of the Temple and of Jerusalem. Jews who manage to find a good life in the absence of this dream are on their way to annihilation as a distinct people no matter what their level of observance may be.
There is a famous saying in Yiddish, S’is shver zu zein a Yid! “It’s hard to be a Jew.” Israel has lost far many more Jews through its history to this statement than to the persuasive power of foreign ideologies.
The spiritual input of the Purim holiday is provided to counter this tendency. In essence, it comes to counter the protest of coercion. We see the Torah as coercion as long as we feel that strict observance is impractical and burdensome in the context of the realities within which we are forced to live. But Jews in exile must be able to find joy in the practice of Judaism to be able to maintain their commitment to Judaism as the focus of their existence. They must still feel that despite all the hardships of exile, their commitment to the Torah is the force that gives them life.
When they were faced with Haman’s edict, the Jewish people found the strength to reach deep into their collective soul. Israel realized that the physical annihilation which threatened them was an indication of the spiritual level to which they had sunk. They were threatened with outward physical annihilation only because they were close to dying as a people spiritually on the inside. They reexamined their attitude to their own commitment to Judaism, located the protest of coercion in their collective Jewish soul, and gave it up for good. As a result, the physical edict was rescinded and the Jews were blessed with “light, happiness, joy and honor.”
The joy that comes from Torah observance under seemingly unfavorable circumstances is the spiritual input that God offers on Purim. May we all merit receiving a powerful dose of it.