RAV YITZCHAK HUTNER zt'l (in PACHAD YITZCHAK, Yom Kippur 5, Pesach 60 (and notes to Pesach 5:2), Shavuos 25:9) offers a penetrating insight based on the Talmud.
Rav Hutner explains that the three differences between this world and the next as described by the Talmud and by Rashi in Devarim are inherently related to each other. In this world, we do not perceive things the way they really are; reality is blurred, and Hashem's presence is not clearly recognized by all. If we would be able to see Hashem's good and perfection clearly, His true essence as One would be obvious. In the World to Come, reality will no longer be blurred, and it will be apparent to all that everything is good. At that time, the nations of the world will proclaim Hashem's Oneness together with us.
Accordingly, all manifestations of Hashem's attribute as "One" are based on the clarity of Hashem's presence that will be evident in the World to Come.
The truth is that even in this world it is possible, to a certain degree, to disperse the clouds that blur man's perception and understanding of reality and to feel the omnipresence of the Divine will. This is because even in this world, no true "bad" or "injustice" is ever wrought. Everything that transpires is the Divine design and is intended to be for our ultimate good (see Berachos 60b). Although the ultimate purpose behind what occurs in this world is often hidden from our perception, the reality is that it is the Divine plan. When we strive to recognize the Divine plan and to accept it, we gain a "glimpse" of the Creator.
The moment at which it is most imperative that we experience the clarity of the presence of Hashem is when we declare, "Shema Yisrael Hashem Elokeinu Hashem Echad," and proclaim the Oneness of Hashem. As Rashi explains, this exclamation expresses our longing for the world in which Hashem's presence will be fully revealed and He will be recognized as One. When we recite this verse, we attempt to gain clarity of Hashem's Oneness in this world of confusion by finding the hidden, inherent good that exists in everything that happens and that exists in this world.
One more word about what Rabbis have said which is very important to this discussion is that very often Rabbis change their rulings on questions as times changes or as circumstances dictate. An example: In the 1990’s there were Rabbis that cautioned about listening to the Facilitated Communications individuals as marking them as true messengers from Shamayim. Why? The FC individuals were, at that time, without a track record of making statements that came true. The Rabbis were totally correct in cautioning us -- then. Here we are 15 years later and the same Rabbis have emphatically stated that these individuals have satisfied the prophecy of Bava Basra 12b, that prophecy has been given to the Shotim and the children (this is a long discussion that has been discussed already – several times) and also that they have satisfied the test of a prophet given to us in the Torah.