Parshat Shelach

Bamidbar 13:1-3
The LORD spoke to Moses, saying, “Send men to scout the land of Canaan, which I am giving to the Israelite people; send one man from each of their ancestral tribes, each one a chieftain among them.” So Moses, by the LORD’s command, sent them out from the wilderness of Paran, all the men being leaders of the Israelites.
Bamidbar 13:32
[They said,] “The country we traversed and scouted is one that devours its settlers.”
The spies were the elite of the Israelite people. They were not simple cowards. At least initially they did not lie about what they saw. What is their sin?
Rabbi Adin Steinsaltz
Life in the wilderness is almost like being part of a Kollel, whose members receive a monthly stipend to support their full-time Torah study. The Jews in the wilderness received manna morning and evening, and were provided with all their basic worldly needs … In this respect, entering the Land is really a downward step … When one lives in the wilderness, one can live a complete spiritual life. But when one enters the Land of Israel,  one’s spirituality is placed in extreme danger.
The problem of entering the Land is the problem of assuming responsibility for the physical, financial, and practical sides of life. All of this responsibility means that one no longer lives in a calm world, where he can sit in peace and study Torah.
When the spies say that the Land consumes its inhabitants, they are basically saying that this is a normal country, a land like all others. Don’t think that every morning there will be a miracle, that sustenance will fall from the sky. It might be a wonderful land, but still, people are born there and people die there.
[Speaking of modern Israel -] But when one lives in one’s own land, all these constant responsibilities — concerns of war and diplomacy, current events, and other matters — become an integral part of one’s life. … The United States is a country where one can choose for oneself the pleasant elements and ignore the others. But when one comes to one’s own country, one must deal with everything; there is no way of evading it. Every normal country requires a certain amount of Shabbat desecration. Even on Yom Kippur, there are all sorts of vital services that must operate around the clock.
Moses regards life in the material world as a challenge and treats it as a goal to strive for, in spite of the problems involved.
The spies are the ones who introduced the view that the physical is dirty and undesirable, and that one must adhere strictly to the spiritual.
almost the entire Torah relates to this world, because there is great significance in the material. … the material world has greater potential for powerful spirituality than the world of the spirit itself.
In a certain sense, the entry into the Land of Israel is like Creation and the dangers it entailed. When God created the world, He chose to dwell down below in the material, physical world.