Another factor in the meraglim's error is that they lost sight of Hashem's love for us. They thought that after sinning with the egel and other aveiros, we lost Hashem's love, and He wouldn't perform miracles for us. The Gemara (Kiddushin 36.) says, כך ובין כך בין בנים קרוים אתם, even after we sin, we are still called Hashem's beloved children. Aveiros don't destroy Hashem's everlasting love and bond with the Jewish nation. And due to Hashem's love, they should have known that He would bring them to Eretz Yisrael with great miracles, regardless of their past deeds.
After hearing the meraglim's report, the nation cried bitterly, as it states (14:1) כל ותשא ההוא בלילה העם ויבכו קולם את העדה, "The entire nation raised their voices and the nation wept that night." That night was Tisha b'Av. Hashem said, "You cried for no reason, בכיה חנם של, I will establish for you a reason to cry in all generations, לדורות בכיה" (Sotah 35.). This is the reason the Beis HaMikdash was destroyed on Tisha b'Av, and there is a לדורות בכיה, a reason to cry in all generations.
They cried because they thought that Hashem didn't love them and that He wanted them to die at war, r'l. As it states (Devarim 1:27) הוציאנו 'ה בשנאת ותאמרו באהליכם ותרגנו להשמידנו האמרי ביד אתנו לתת מצרים מארץ, "You slandered in your tents and said, 'Because of Hashem's hatred for us, did He take us out of the land of Egypt, to deliver us into the hand of the Amorite to destroy us.'"
It was the false thought that Hashem didn't love them that caused them to cry. This resulted in Hashem saying, "You cried for no reason. Therefore, there will be a reason to cry in all generations." This false thought brought about the churban Beis HaMikdash, the root of galus. The belief that Hashem loves us unconditionally will result in the redemption.
The Toldos writes in the name of the Baal Shem Tov zt'l that the galus is so long because we don't say the brachah of אהבת עולם (before shema) at length. Which part of the brachah should we recite at length? Many assume that it is בתורתך עינינו והאר, where we plead for success in Torah, etc. But we can explain that most important is to say at length, and to concentrate, on the words אהבתנו עולם אהבת, and מלכנו וקרבתנו and similar words that express Hashem's love to us. Thinking that Hashem hates us resulted in the Churban and the galus, so the realization that Hashem loves us will result in the geulah.
We understand that חנם של שמחה, when we are happy for no specific reason, just because we know that Hashem wants us to be happy, will result in לדורות שמחה, good times and happiness for generations."
