The Torah reading begins with the pasuk: "You are all standing (nitzavim) before Hashem... every person in Israel" (Devarim 29:9). Within the few dozen p’sukim before and after this pasuk, the stress on the entirety of the nation as audience comes up repeatedly (see ibid.:1; ibid. 31:30).
In many of its appearances in the Torah, the word nitzav has a special meaning or connotation. In the Torah reading for fast days, which includes the thirteen middot that are the basis of the Selichot (Shemot 33), the root comes up three times, referring to Hashem or to Moshe standing in a special, holy context. The gemara (Rosh Hashanah 17b) says something that "if there weren’t a pasuk, it would be forbidden to say": "Hashem covered Himself like a chazan and taught Moshe how to daven. Hashem told Moshe that whenever Bnei Yisrael sin, they should daven in that manner and Hashem will forgive them." Rav Soloveitchik learned from here that during the High Holy Days, the chazan not only represents the people but represents Hashem.
Other places that the root of nitzav comes up include regarding the three angels who stood before Avraham and Avraham’s servant standing at the spring when he asked Hashem for special guidance. Later on in Tanach, Chana was described using this term when she stood in the Mishkan before Eili begging for a child. Later on, her son, Shmuel, stood before King Shaul’s officers and caused them to prophesy. The common denominator in these cases and others is a certain element of Divine Presence that was present in each context.
The connection between nitzav and Divine Presence is explicit in Chazal in regard to Moshe’s sister, Miriam. The Torah says that she was standing at a distance, seeing what would befall her baby brother. The gemara (Sota 11a) derives from the use of the root nitzav that she was undergoing prophecy. (We might mention that the root’s spiritual connotation may also be related to the word matzeiva [monument for sacrifices], which was beloved by Hashem before it was misappropriated for idol worship.)
We return to our parasha and note that nitzavim was accomplished there very specifically in the presence of the entirety of the Jewish people. We can learn from here that in order for the people to merit the special experience of Divine Revelation, it was necessary for the nation to stand as one. As the Torah stresses, the assemblage had to include the mighty and accomplished alongside the down-trodden and simple people. At times of crisis and internal strife, it is important for us to remember that unity is our greatest secret for success; it enables us to appeal to Hashem’s attributes to increase the Attribute of Mercy.