The action of the scouts is one of the greatest tragedies that happened to our nation. Five terrible events happened to our ancestors on the ninth of Av, and one of them was that it was decreed that they would not be allowed to enter the Land of Israel. How can it be that ten of the most prominent men of Israel, who were considered great and holy men even in the era of Moses, would become "disgusted with the desirable land" (see Psalms 106:24), and lead the others in committing a sin? The sin of the scouts is more serious than other sins, whose purpose is usually to "jump the gun" and cause an event to take place earlier than it might have happened. For example, in the sin of the Golden Calf the people wanted the Shechina to appear earlier than the proper time. When Adam sinned he wanted to eat from the forbidden fruit before it was allowed. But a sin of wanting to cause a delay, such as in this case, when the proper time has arrived and the men did not want to partake of the good fruits of the land, shows that the people felt apathy and were disconnected. And that is what makes it such a serious matter.
The motive of the scouts was different than that of the people. The scouts, who were important men, were guided by spiritual considerations. They feared that becoming involved in running a real country might bring the nation to a state which would make them forget the Holy One, Blessed be He, and that they would not be able to reach spiritual renewal after their lapse. Thus, they felt that it would be preferable to continue living in exile rather than to have to contend with the difficulties of living in the land. This was a reason to praise them, but it was also detrimental, because it implied a lack of faith on their part.
According to the Zohar, the scouts sinned because they knew that in the new land Moses would replace the leaders with other men, and they would no longer have the position of tribal heads. This was not a simple craving to continue on as leaders, but rather it entailed a deep understanding that there are two types of leaders for the nation of Israel: those who are suitable for a time of exile and those who are suitable for the Land of Israel. Since the scouts loved the people very much and felt that they were the very best leaders that the nation could have, they feared that the new leaders that would be appointed in the land would not be as good. They therefore felt as a "temporary ruling" that it would be best not to observe the mitzva of settling in the Land of Israel, so that they could continue to lead the nation.
In order to convince the multitudes of the people that it was not to their advantage to enter the land, the scouts, for the first time in history, made use of the claim that "mortal danger takes precedence over settling the land." In a war, people can be hurt, heaven forbid, and since mortal danger takes precedence over all the mitzvot of the Torah, this war should not be fought. And because of this the scouts were punished.
The Torah tells us that such a claim might appear, so that we will know how to deal with it later in our history. Joshua and Caleb were right when they said that the command to wage war takes precedence over the fear of mortal danger. They presented a minor view, opposed by most of the prominent men in the nation. "Let us rise up and take possession of it" [Numbers 13:30]. In a way that is different from the Torah in general, the final ruling in this case is the opinion of the minority – that the conquest of the land is an obligation.
When the nation returns to the land, Joshua and Caleb are the leaders because of their strengths. They are from the tribes of Judah and Ephraim, and they carry with them messianic strength – Messiah Son of Joseph and Messiah Son of David. They renew the honor of the nation and the honor of those who study Torah in the era of redemption.