In this week’s Parashah, Bnei Yisrael are commanded to contribute a half-Shekel to a communal fund, where the total amount of Shekalim would then be counted. Thus, a census would take place without using a direct head-count, a method specifically prohibited by Hashem. The reason for this prohibition is clearly stated along with the commandment to donate these coins: “VeLo Yihyeh VaHem Negef BiFkod Otam,” “So that a plague will not strike them in counting them” (Shemot 30:12). The fulfillment of this sin is clearly illustrated in King David’s violation of this commandment, where a plague ensues as a punishment for a direct head-count (Shmuel II 24).
However, the Torah is also trying to communicate another message from this prohibition. The reason why Bnei Yisrael are specifically commanded to give a half-Shekel instead of a whole Shekel is because without everyone else in the nation, each individual is only “half”; he needs another half to complete himself. Therefore, Hashem warns Bnei Yisrael to always know that they are incomplete without each other, and that they must cooperate with each other now that they were a full nation. That is why they were commanded this at Har Sinai; it was an integral lesson for the new nation to learn. As long as Bnei Yisrael would take this message to heart and be united, Hashem would not bring a plague upon them, but once leaders would count them as whole entities (such as through a head count), they would not have the same protection against a divine plague. Once we begin to break away and work against each other, there is nothing to stop a plague from afflicting us.
If we all remain united as a people, we will have the Almighty’s protection from harm.