Shavuos commemorates Mattan Torah, the Giving of the Torah. A spectacular event, the Revelation at Sinai, when the L-RD gave B’nei Yisrael the Commandments. This was the culmination of the Exodus from Egypt. Being made a people unto the L-RD our bond to Him was signified with the commandments, presented as a ketubah (marriage contract) to the Bride (K’lal Yisrael). Our sovereignty as a nation begins here; the declaration being made first, with Matan Torah, then, we were brought into the Land: a people first, then, we were given a country.
Today, the Torah should still speak to our everyday lives; otherwise, Mattan Torah, becomes a glorious event, disconnected from our current times. When we learn Torah, we should feel compelled to incorporate these ideas into our lives; inasmuch that the Torah still has relevancy after so many generations. The Ten Commandments are a good place to start; perhaps, simply by naming them; then, reflecting on each one in relation to our lives.
Although we may believe in G-d, the additional question to pose to ourselves is whether or not we have accepted His Sovereignty. In this sense, as mentioned in commentary (Baal Halachos Gedolos), the first commandment is a call to believe in the existence of G-d; subsequently, accepting His authority as the source of the commandments. When we accept G-d’s Sovereignty, then the commandments become authoritative; otherwise, the commandments could be misconstrued as relative.
Consider as well, that here is a difference between accepting the commandments for ourselves, because we recognize the inherent wisdom in them, akin to the moral perspective that we uphold, versus accepting the commandments as the divine words of G-d; and, as an expression of His expectations of us, regardless of our own perspective. The Jewish people are bound to the commandments, regardless of whatever our perspective may be; therefore, the primacy of the first commandment is that the authority of all of the other commandments are hinged upon the first.
“I am the L-rd your G-d, who brought you out of the land of Egypt.”
– Exodus 20:2