Rashi famously begins his commentary to Sefer Bereshis with the words of a medrash:

Rabbi Yitzchak said, “The Torah should have begun with Kiddush Ha-Chodesh (Sanctification of the New Month), which is the first mitzvah commanded to B’nei Yisroel (and is found in Sefer Shemos). Why did the Torah instead begin with Bereshis (Creation)? Due to the pasuk (verse – Tehillim 111:6) that states, ‘The strength of His actions did He relate to His people, to give them the inheritance of nations’, which justifies Hashem giving Eretz Yisroel to the Jewish People. For should the nations of the world accuse the Jews of being thieves by conquering and possessing the Canaanite lands, the Jews can reply that the entire world belongs to Ha-Kadosh Baruch Hu (the Holy One, blessed is He), Who created it gave it to whom He saw fit. He willingly gave it (Eretz Yisroel) to the nations of Canaan and willingly took it from them and gave it to us.”

The obvious question is how will B’nei Yisroel invoking Bereshis as the basis of our right to Eretz Yisroel convince the nations that we are not thieves regarding the Land? The nations of the world do not accept the Torah and will surely reject our use of it as proof for our rights to the Eretz Yisroel. What is the medrash quoted by Rashi actually telling us?   

I believe that there are two answers, which form a unified idea.

Although the nations of the world do not accept the Torah, at least not as their final authority, the Torah is the source of profound universal and eternal truths which people do indeed accept, at least on a subconscious level, despite their denial thereof. The unparalleled and unique primacy of man as the most advanced creature in the biosphere; people’s almost uncontrollable inclination to break rules and violate their dearest values in the face of carnal temptation, as well as for money, personal honor and control over others; deep-seated characteristics of the male and female personalities, and of human nature in general, especially pertaining to siblings and their rivalries; the role of the Jew in Golus (Exile) as accused and persecuted, thereby forced to scheme for his survival, as per the prototype of Yaakov Avinu in Lavan’s house - as well as paramount notions of an all-powerful Being and Force of Creation, of a higher morality, of the prohibitions of murder, theft, sexual deviance, and so much more - are universal concepts that the Torah introduces in Sefer Bereshis. The world at large has accepted these ideas outright or at least subconsciously, and they have become the bedrock of human existence.

Among these universal truisms is also the divine and historical connection of the Jewish People to Eretz Yisroel. Although this connection might be robustly denied by the nations of the world, in their innermost minds and souls does it resonate, and when the Jews stake their claim to the Land as articulated by the medrash, it strikes an intuitive chord, as much as the nations will consciously deny and fight it. The extreme and inexplicable fixation of world powers over Jewish reign in a minuscule sliver of land, while gross injustices are committed elsewhere by the various nations with usually minimal or no condemnation by anyone, surely indicates that regarding Eretz Yisroel, a raw nerve has been struck, for the nations cannot shake themselves of the truism that is the Jewish People’s ontological connection with the Land; the nations are obsessed with attempts to deny this connection and they relentlessly pursue irrational means in every effort to sever it, as deep down, they know that the connection is divinely ordained, and it often bothers them to no end.  

There is another perspective to this all. When B’nei Yisroel lay forth their claim to Eretz Yisroel based on the Torah, it is not for the sake of the nations that B'nei Yisroel need to do so - for even though the nations deep down accept the words of B’nei Yisroel, fierce denial and refusal will usually be expressed by the nations, until the time of Moshiach. What then is the function of B’nei Yisroel’s assertion of their right to Eretz Yisroel based on the Torah, on the story of Bereshis? The function is to encourage and inspire B’nei Yisroel themselves. We must always know that our rights to Eretz Yisroel are by virtue of Hashem creating and gifting the Land to us; once we overlook this and resort solely to pragmatic arguments, as powerful and true as they often are, we strip away notions of sanctity and of our relationship with Hashem through the Land. Therefore, our instinctive and immediate claim to Eretz Yisroel must flow from the words of the Torah, which affirm Hashem’s authority over the world and His unchallenged ability to apportion its lands to whomever He sees fit. Just as ultimately, the Makkos Mitzrayim (Plagues in Egypt) were designed to forge a permanent impression on B’nei Yisroel and not on the Mitzrim, for any impact on Mitzrayim was temporary and did not endure (v. Ibn Ezra on Shemos 9:16), so too do we affirm our divinely-pledged claim to Eretz Yisroel for our sake, to fortify our own emunah (belief).  

One might still ask why, according to the medrash cited by Rashi, the Torah did not simply present the story of Bereshis (and Hashem’s promise of the Land of Israel to B’nei Yisroel) and then jump to the mitzvah of Kiddush Ha-Chodesh in Sefer Shemos, if the purpose of the Bereshis story is solely to affirm our divine right to Eretz Yisroel. The answer is that the entirety of Sefer Bereshis sets forth the cardinal principles of the human experience, as described above, and it also teaches us by example of the Avos (Patriarchs) and their families how to live as Jews. The unique and exceptional character qualities of the Avos and Imahos, their interactions with Hashem and with other people, and how they were impacted by all that transpired in the narratives of their lives, have created eternal blueprints and paths for us to follow. Rabbi Yitzchak’s explanation of the foundational function of the inceptive Bereshis text is an illustration of this broader idea that encompasses the entirety of Sefer Bereshis. Before we commence the halachos (laws) of the Torah, Rabbi Yitzchak teaches that we must be presented with the Torah’s core values, ideals and lifestyle, as embodied by the lessons of Creation and its aftermath, and of the holy personalities of the Avos and Imahos and of their experiences in Sefer Bereshis.

This is the deeper and paramount significance of the first words of Rashi in his Torah commentary.