This Torah portion contains a re-telling of the Ten Commandments (which in the Jewish tradition are the Ten Utterances), and the Shema, or statement of faith, probably the line in the whole Torah that best condenses the Jewish faith into six words.
The Ten Commandments are numbered differently by Jews than by Christians. "I am the LORD thy God" is a preamble to the Christians, but the first utterance to the Jews. Jews also lump all examples of covetous behavior into one utterance, whereas Christians separate the first example of covetousness (house in Exodus, wife from Deuteronomy) from the others. The Jewish fourth utterance (the Christian third commandment) begins with a different word in Exodus than in Deuteronomy. In Exodus, the word is zachor, or "remember". In Deuteronomy, the word is shamor, or "guard", or "protect". So the line is "Remember the sabbath day, to keep it holy," in Exodus, and "Keep the sabbath day to sanctify it, as the Lord thy God has commanded thee."
There are other differences, and they are worth noting, but the shamor/zachor difference is fascinating to Judaism. One midrash says that God said both words simultaneously at Sinai, and that Moses had to relate it twice to provide both concepts. The great erotic/mystical poem L'cha Dodi, that Jews recite on Friday evenings has the line "shamor v'zachor b'dibur echad," which can be translated as "shamor and zachor in a single utterance".
The idea is that the Divine happens on a level that transcends language---that language is a mediator and that gnosis is too immediate to have language as a filter. Moses has to share his experiences of gnosis in a medium that the Israelites understand: their own language. But Moses and God have an intimacy more direct than language. In seeking an experience of the Divine, one begins with words and later eschews them in silence.
The Shema [Deuteronomy 6:4} is one of the holiest prayers in Judaism. It is the testament of faith of the Jewish people. The King James Bible has it and the next paragraph as:
"Hear, O Israel: The Lord our God is one Lord:
And thou shalt love the Lord thy God with all thine heart, and with all thy soul, and with all thy might. And these words, which I command thee this day, shall be in thine heart: And thou shalt teach them diligently unto thy children, and shalt talk of them when thou sittest in thine house, and when thou walkest by the way, and when thou liest down, and when thou risest up. And thou shalt bind them for a sign upon thine hand, and they shall be as frontlets between thine eyes. And thou shalt write them upon the posts of thy house, and on thy gates."Shema yisra'el YHVH Eloheinu YHVH echad. Listen, Israel! YHVH is our God. YHVH is one (unity). More metaphorically, yisra'el is one who wrestled with God, so everyone who wrestles with the concept of God, who struggles with faith, whose faith is interlaced with serious doubts. Eloheinu could be a noun "our God", or it could be a verb "that which Gods us". So it could be interpreted as: "Listen, those of you grappling with the concept of God! The fourfold ineffable Name that balances the four elements, that was, is, and shall be is Godding us. This ineffable Force that penetrates time and space is the unifying Force in the universe." That's a bit more resonant for me.
The first line of the Shema is considered so holy that Jews in immediate peril of their lives will say it to make it the last thing they say in this life. There was a story of an IDF soldier who spotted a discharged PLO grenade, and jumped on it and recited the first line of the Shema. It is said that Rabbi Akiva, who was executed by the Romans by having his skin torn off with iron combs, remained calm until he died, when he recited the Shema just before expiring.