In a play on words, Rabbi Nosson Adler takes this idea a step further. One of the epithets for the yetzer hara (evil inclination) is a mountain. For example, the Talmud states that when righteous people are judged in the future, the yetzer hara will appear as a mountain they overcame through hard work and self-restraint. The primary goal of the yetzer hara is to bring strife among the Jewish people. But at the time of the Revelation at Sinai, Jews stood in direct opposition to this inclination of interpersonal indecency; as the verse states, they were "opposite the mountain." Jews were united in purpose and spirit as never before - and arguably, we have never been that way since.
If we are ever to regain the kind of cohesiveness achieved thousands of years ago, we first have to understand what needs to be accomplished. Unity does not mean sameness. We don't have to be exactly alike in terms of dress, ritual observance or political ideology. While civilization is dependent upon the objective ethical principles of the Torah, we can't be self-centered and think that others must be exactly like us in the more subjective areas of life. Unity means togetherness despite differences. It denotes a harmony of related parts where there would usually be discord. In other words, everyone is able to maintain their uniqueness, and at the same time recognize the important roles other people play in God's grand scheme of events.
Just as the human body has different organs that serve specific functions, so too the Jewish people have different individuals who each serve a particular purpose to the nation as a whole. Some Jews spend their days studying religious texts and engaging in ritual observance, while others pursue science, law, math, art or business-related studies and professions. Despite these significant differences in lifestyle, never forget that without a single, beating heart (representing how we treat one another), the body cannot survive. So the next time you have trouble with a fellow Jew or group of Jews, keep this in mind. Our future literally depends on it.