In Parshas Acharei Mos, we learn that Eretz Yisroel is unable to tolerate arayos (immorality) and that it will expel people who involve themselves in such behaviors. Hashem's hashgacha (divine providence) is directly upon Klal Yisroel living in Eretz Yisroel, and it is more potent there than any other place Jewish people live. When we say Shema, we are declaring our emunah in Hashem and in His direct hashgacha. In galus, Hashem turns His face away and acts as though He is not directly involved. As Bnei Yisroel we already believe in Hashem's involvement, and when the geulah arrives the entire world will be aware of His presence.