Reading here that God is one, most Jews for centuries have ruled out the possibility that Jesus of Nazareth could be the Son of God, on the same divine plane as God the Father.
Early Catholic theologians, reading the same verse, struggled to formulate in the doctrine of the Trinity a God consisting of the Father, the Son and the Holy Spirit, with these being distinct persons yet at the same time a single triune God.
How, then, should we understand this verse?
One of the primary principles for understanding the Bible is that we must consider all the scriptures on a subject. Only then will we come to a complete and accurate understanding of the matter.
Other biblical passages clearly tell us that two distinct individuals, the Father and Jesus Christ the Son, are both God (Hebrews 1:8 Hebrews 1:8But to the Son he said, Your throne, O God, is for ever and ever: a scepter of righteousness is the scepter of your kingdom.
American King James Version×; John 1:1 John 1:1In the beginning was the Word, and the Word was with God, and the Word was God.
American King James Version×, John 1:14 John 1:14And the Word was made flesh, and dwelled among us, (and we beheld his glory, the glory as of the only begotten of the Father,) full of grace and truth.
American King James Version×). Therefore we should consider whether the Shema is commenting on the numerical oneness of God, or something else entirely.
Multiple meanings of the Hebrew word translated "one"
Those who study the Hebrew language are challenged by the fact that Hebrew has a much more limited vocabulary compared to other languages such as English. What this means is that a single Hebrew word can and often does have multiple meanings, making precise translation difficult.
A good example of this is the Hebrew word echad, translated "one" in Deuteronomy 6:4 Deuteronomy 6:4Hear, O Israel: The LORD our God is one LORD:
American King James Version×. Its meanings include the number one, but also such associated meanings as "one and the same," "as one man, together [unified]," "each, every," "one after another" and "first [in sequence or importance]" (Brown, Driver and Briggs, A Hebrew and English Lexicon of the Old Testament, 1951, p. 25). It can also be rendered "alone," as the New Revised Standard Version translates it here (William Holladay, A Concise Hebrew and Aramaic Lexicon of the Old Testament, 1972, p. 9). As with many other Hebrew words, the exact meaning is best determined by context.
In this case, several interpretations could be both grammatically correct and consistent with other biblical statements.
In the Shema, Moses may have simply been telling the Israelites that the true God, their God, was to be first—the highest priority—in their hearts and minds. The young nation had risen from slavery in a culture in which the Egyptians believed in many gods, and they were poised to enter a land whose inhabitants were steeped in the worship of many supposed gods and goddesses of fertility, rain, war, journeys, etc. Through Moses, God sternly warned the Israelites of the dangers of abandoning Him to follow other gods.
This interpretation—that God is to be the Israelites' first priority—has strong support in the context. In the very next verse Moses continues, "You shall love the Lord your God with all your heart, with all your soul, and with all your strength."
This passage is at the heart of a several-chapters-long discussion of the benefits and blessings of wholeheartedly following God and avoiding the idolatrous practices of the people who were to be driven out of the Promised Land. Jesus Himself quoted Deuteronomy 6:4-5 Deuteronomy 6:4-5  Hear, O Israel: The LORD our God is one LORD:
 And you shall love the LORD your God with all your heart, and with all your soul, and with all your might.
American King James Version×as the "first and great commandment" in the law (Matthew 22:36-38 Matthew 22:36-38  Master, which is the great commandment in the law?  Jesus said to him, You shall love the Lord your God with all your heart, and with all your soul, and with all your mind.  This is the first and great commandment.
American King James Version×; Mark 12:28-30 Mark 12:28-30  And one of the scribes came, and having heard them reasoning together, and perceiving that he had answered them well, asked him, Which is the first commandment of all?  And Jesus answered him, The first of all the commandments is, Hear, O Israel; The Lord our God is one Lord:  And you shall love the Lord your God with all your heart, and with all your soul, and with all your mind, and with all your strength: this is the first commandment.
American King James Version×).
Another meaning of the Hebrew word echad, "alone," fits this context as well. That is, the true God alone was to be Israel's God; the Israelites were to have no other.
This may be how a scribe who heard Jesus quote the verse in Mark 12:29-30 Mark 12:29-30  And Jesus answered him, The first of all the commandments is, Hear, O Israel; The Lord our God is one Lord:
 And you shall love the Lord your God with all your heart, and with all your soul, and with all your mind, and with all your strength: this is the first commandment.
American King James Version×understood it. The scribe responded in Mark 12:32 Mark 12:32And the scribe said to him, Well, Master, you have said the truth: for there is one God; and there is none other but he:
American King James Version×(NRSV): "You are right, Teacher; you have truly said that ‘he is one [Greek heis, which corresponds to echad in its multiple meanings], and besides him there is no other'"—which seems to indicate that this is what the scribe understood the word rendered "one" to mean in the expression (in essence, "alone").
This would not rule out Jesus Christ from being God along with the Father. Rather, there is no other God apart from the true God—that is, outside the God family or God "kind" now consisting of two divine Beings, the Father and the Son. In short, the God family alone is God.
Another view of the Shema is based on the root word from which echad is derived—achad. This word means "to unify" or "go one way or other" (Strong's Exhaustive Concordance of the Bible). In other words, echad can also mean in unity or a group united as one.
Instances where "one" can mean a group
In several verses echad clearly has the meaning of more than one person united as a group. In Genesis 11:6 Genesis 11:6And the LORD said, Behold, the people is one, and they have all one language; and this they begin to do: and now nothing will be restrained from them, which they have imagined to do.
American King James Version×God says of those building the tower of Babel, "Indeed the people are one [echad] . . ." In Genesis 2:24 Genesis 2:24Therefore shall a man leave his father and his mother, and shall join to his wife: and they shall be one flesh.
American King James Version×He says, "Therefore a man shall leave his father and mother and be joined to his wife, and they shall become one [echad] flesh."
When we read of a large group of people being one or a man and wife becoming one flesh in marital union, we understand that multiple individuals are involved. We do not assume that separate individuals, though united in spirit and purpose, have physically merged to become a single being.
God the Father and Jesus Christ the Son are clearly of one mind and purpose. Jesus said of His mission, "My food is to do the will of Him who sent Me, and to finish His work" and "I do not seek My own will but the will of the Father who sent Me" (John 4:34 John 4:34Jesus said to them, My meat is to do the will of him that sent me, and to finish his work.
American King James Version×; John 5:30 John 5:30I can of my own self do nothing: as I hear, I judge: and my judgment is just; because I seek not my own will, but the will of the Father which has sent me.
American King James Version×).
Describing Their relationship, Jesus said, "I and My Father are one" (John 10:30 John 10:30I and my Father are one.
American King James Version×). Christ prayed that His followers, both then and in the future, would be unified in mind and purpose just as He and the Father were. "I do not pray for these [disciples] alone," He said, "but also for those who will believe in Me through their word; that they all may be one, as You, Father, are in Me, and I in You; that they also may be one in Us" (John 17:20-21 John 17:20-21  Neither pray I for these alone, but for them also which shall believe on me through their word;  That they all may be one; as you, Father, are in me, and I in you, that they also may be one in us: that the world may believe that you have sent me.
American King James Version×). Further explanation of God's oneness, in the sense of unity, may be found throughout this chapter of the booklet.
No matter which translation we accept—whether "The Lord our God, the Lord is first," "The Lord is our God, the Lord alone," or "The Lord our God, the Lord is one [in unity]"—none limits God to a singular being. And in light of these scriptures we've seen and others, it is clear that God is a plurality of beings—a plurality in unity. In other words, God the Father and Jesus the Son form a family perfectly united as one.