"I am HaShem your G-d, Who brought you out of the land of Egypt, from the house of slavery." (Shemos 20:2)
The words "I am HaShem your G-d" command Klal Yisrael to know and believe that HaShem exists and is G-d to them. This belief includes that HaShem is an existing Being; that He preceded every other being; that He created everything by His will and power; and that He is a G-d to them, and that they are required to serve Him. In addition, HaShem said, "Who brought you our of the land of Egypt," because the Exodus proved the existence, omnipotence, and free will of HaShem. The Exodus also proved that HaShem created the universe, for He changed the very course of nature. The verse concludes, "from the house of slavery," teaching that we are required to accept and serve the great, glorious, and awesome HaShem as our G-d, because He redeemed us from Egyptian slavery.
The "First Commandment" contains all the fundamental concepts of belief in HaShem. Specifically, that HaShem is the eternal, all-powerful Creator, as well as, HaShem's special relationship - and salvation - of Klal Yisrael.
Envision that you are standing at Mount Sinai, together with the entire Nation of Israel. Imagine you hear HaShem say, "I am HaShem your G-d, Who brought you out of the land of Egypt, from the house of slavery." Sense how the holy, awesome words spoken by HaShem, penetrate your heart and soul, with their powerful truth. Internalize the elements of belief, and strengthen your commitment to accept HaShem as your G-d, and faithfully serve Him.
(Based on the commentary of the Ramban to the Torah)
