Oneness Christians (and the Jews) believe that Deuteronomy 6:4 proves that the Christian belief in the Trinity is wrong. The purpose of this article is to show that the Trinity is not at all contradicted by this verse. If you are interested in this article, you will want to read my 5 part article titled, "More on the Trinity," which is located on this site under Bible Studies. And there are three companion articles for that article under that heading. Those articles are: "The Name Yahweh and God the Father and God the Son: The Name Yahweh and a Listing of Some of the Large Number of Passages in the Hebrew Old Testament Where We Can See God the Son Along with God the Father"; "Who Do We Pray To?"; and "Who Do We Worship?"
Deuteronomy 6:4. "Hear, O Israel! The LORD [Yahweh] is our God, the LORD [Yahweh] is one." I'll quote a sentence from what J. A. Thompson says here. (I had a footnote: "Deuteronomy" [Inter-Varsity Press, 1974], page 121.) "This small section (Deut. 6:4-9) has been known to the Jews for many centuries as the "Shema" (Hebrew, "Hear" ["Shema" is the Hebrew word translated "Hear" at the beginning of Deut. 6:4.]) and has been recited along with 11:13-21 and Numbers 15:37-41 as a daily prayer."
Based on what I have heard and read, Deut. 6:4 is the number one verse used (sincerely used) by Christians who deny the Trinity to argue for a oneness view of God. I am quite sure, however, that this verse was written for the sole purpose of declaring that the God of Israel (the God of creation, the God of the Bible, the God of Abraham) is the only true God. Some of the gods of the nations existed all right, but they were evil beings under Satan, and they were far from being in the class of the only true God, the One who had created every being and every thing that exists. (God didn't create Satan or any of the angels evil, but Satan rebelled against God through pride, and a third of the angels followed him in his rebellion.)
For one thing, it was totally necessary for the people of Israel to understand what a serious sin it was for them to worship the gods which all of the peoples apart from Israel were worshipping in the ancient world, and had been worshipping for a long time. All too often many of the people of Israel succumbed to the temptation to worship the gods of the nations. That sin went directly against the first commandment of the Ten Commandments. See Ex. 20:1-5; Deut. 5:6-10; and 6:5.
Deuteronomy 6:4 was not written to deny the Trinity that God progressively revealed, starting in the Old Testament, including in the five books of Moses. As my paper titled, "The Name Yahweh and God the Father and God the Son: The Name Yahweh and a Listing of Some of the Large Number of Passages in the Hebrew Old Testament Where We Can See God the Son Along with God the Father" demonstrates, there are a large number of passages in the Old Testament where we can see the Person of God the Son. It is true, however, that we needed the light of the New Testament to adequately understand that glorious Person and the Trinity.
Verses like Deut. 4:35, 39 communicate the same message as Deut. 6:4 with the words, "To you it was shown that you might know that the LORD [Yahweh], He is God; THERE IS NO OTHER BESIDES HIM" and "Know therefore today, and take it to your heart, that the LORD [Yahweh], He is God in heaven above and on the earth below; THERE IS NO OTHER." There is only one God!
I'll quote a few sentences from what Earl S. Calland says here (I had a footnote: "Expositor's Bible Commentary," Vol. 3 [Zondervan, 1992], page 65.) to show that the Hebrew word ("echad") that is translated "one" in Deut. 6:4 was sometimes used of a oneness that consisted of more than one part, "To the Jews verse 4 is not only an assertion of monotheism, it is also an assertion of the numerical oneness of God contradictory to the Christian view of the Trinity of the Godhead. This kind of oneness, however, runs contrary to the use of echad in the sense of a unity made up of several parts. In Exod. 25:6, 11, the fifty gold clasps are used to hold the curtains together so that the tent would be a unit (echad). ...."
I'll quote several sentences from page 2 of the 14 page article titled, "The Historic Case for the Trinity" by K. Dayton Hartman (www.answering-islam.org). He is discussing Deut. 6:4 and making the point that the Jews left a lot of room to see some plurality in their one God before the arrival of Christianity. "The possibility of plurality existing in a monotheistic Godhead was an active topic in pre-Christian Jewish theology. (He has a footnote here: "See especially, Larry Hurtado, 'One God, One Lord: Early Christian Devotion and Ancient Jewish Monotheism' [Fortress Press, 1988].") A text that inspired much of this debate is found within Daniel's book of prophecy. In Daniel 7:9, a plurality of thrones exists in heaven, all of which, the text proposes, belong to Yahweh. The text reads, 'I kept looking until the thrones were set up, and the Ancient of Days took His seat....' In the passage there are multiple seats of power (thrones), yet a single being of power (the king). [For the record, Dan. 7:18, 22, and 27 show that the saints will be reigning too; the thrones are for the saints (also see Rev. 20:4-6).] N. T. Wright, commenting on pre-Christian Judaism, points out that, 'Within the most fiercely monotheistic of Jewish circles...there is no suggestion that "monotheism" or praying the Shema, had anything to do with the numerical analysis of the inner being of Israel's God Himself.' (He has a footnote: " 'The New Testament and the People of God' [Fortress Press, 1996], page 259.") ... After reviewing the evidence N. T. Wright concludes that: 'The oneness of Israel's God, the creator, was never an analysis of God's inner existence, but always a polemical doctrine over against paganism and dualism. It was only with the rise of Christianity...that Jews in the second and third centuries reinterpreted "monotheism" and the numerical oneness of the divine being' (He has a footnote, which is the same as the last footnote.)."
A BETTER WAY TO INTERPRET DEUTERONOMY 6:4 After further study and prayerfully considering this verse, I have come to the opinion that the proper way to understand this verse (the way intended by the ultimate Author of the Bible) is to see that the name Yahweh refers to God the Father here, as it typically does throughout the Old Testament, not to the Trinity. This applies to Deut. 4:35, 39 (verses quoted above), and to many similar verses in the Old Testament (including Isa. 43:10, 11; 44:6, 8; 45:6, 21, 22; and 46:9). In most of the verses dealt with in my paper titled, "The Name Yahweh and God the Father and God the Son: The Name Yahweh and a Listing of Some of the Very Large Number of Passages from the Hebrew Old Testament Where We Can See God the Son Along with God the Father," for example, the name Yahweh typically refers the God the Father. The Old Testament was written in the years before God wanted to fully reveal the Person of His Son and the Trinity.
When Jesus first came to Israel, having been born of the virgin, none of the people of Israel understood that the Messiah would be deity. (We will never understand the Trinity until we see that God the Son was to become the God-man and the promised Messiah, and that the Messiah would, therefore, be deity. The deity of the Messiah took the promised new-covenant salvation to a whole new level. To be united with the Messiah is to be united with God the Son, the One who brings us to the Father.) The apostles didn't understand His deity until after His resurrection. They didn't even believe in His resurrection until after He was resurrected, even though He had told them that He would be resurrected on the third day.
God's revelation, which includes His opening the eyes of His people to understand the Scriptures, is progressive (see, for example, Luke 24:25-27, 44-49). The name Yahweh typically refers to God the Father in the Old Testament, even as the word God typically refers to God the Father in the New Testament. And the New Testament has quite a few passages like John 17:3 ("This is eternal life, that they may know You, THE ONLY TRUE GOD [my emphasis], and Jesus Christ whom You have sent."); Rom. 16:26, 27 (I'll read verse 27, "to THE ONLY WISE GOD [God the Father], through Jesus Christ, be the glory forever. Amen!"); 1 Cor. 8:4-6 ("Therefore concerning the eating of things sacrificed to idols, we know that there is no such thing as an idol in the world, and that THERE IS NO GOD BUT ONE [referring to God the Father]. (5) For even if there are so-called gods whether in heaven or on earth, as indeed there are many gods and many lords, (6) yet FOR US THERE IS BUT ONE GOD, THE FATHER, from whom are all things and we exist for Him, and one Lord, Jesus Christ, by whom are all things [These words would be better translated "through whom are all things." God the Father created all things through God the Son.], and we exist through Him."); 1 Cor. 15:27, 28 (I won't quote these verses here, but these verses strongly emphasize the preeminent role of God the Father.); Eph. 4:4-6 ("There is one body and one Spirit [the Holy Spirit], just as you were called in one hope of your calling; (5) one Lord [the Lord Jesus], one faith, one baptism, (6) ONE GOD AND FATHER OF ALL WHO IS OVER ALL AND THROUGH ALL AND IN ALL."); 1 Tim. 1:17 ("Now to the King eternal, immortal, invisible, THE ONLY GOD [referring to God the Father], be honor and glory forever and ever. Amen."); 1 Tim. 2:5 ("For THERE IS ONE GOD, and one mediator also between God and men, the man Christ Jesus...."); 1 Tim. 6:13-16 ("I charge you in the presence of God [God the Father], who gives life to all things, and of Christ Jesus, who testified the good confession before Pontius Pilate, (14) that you keep the commandment without stain or reproach until the appearing of our Lord Jesus Christ, (15) which He [God the Father] will bring about at the proper time - HE WHO IS THE BLESSED AND ONLY SOVEREIGN, the King of kings and Lord of lords, (16) who alone possesses immortality and dwells in inapproachable light, whom no man has seen or can see. To Him be honor and eternal dominion! Amen."); and Jude 1:24, 25 ("Now to Him [God the Father] who is able to keep you from stumbling and to make you stand in the presence of His glory blameless with great joy, (25) TO THE ONLY GOD OUR SAVIOR [referring to God the Father], through Jesus Christ our Lord, be glory, majesty, dominion and authority, before all time and now and forever. Amen.")
Verses like the ones I just quoted from the New Testament that greatly exalt God the Father and His preeminent role (calling Him "the only God" and such expressions) do not diminish the fact that the Bible (and especially the New Testament) clearly teaches the full deity of God the Son (and the Holy Spirit). For one thing, the name Yahweh is used on occasion for God the Son in the Old Testament and the word God is used for Him several times in the New Testament, which strongly teaches His full deity. (The deity of Jesus Christ is rather thoroughly discussed in the four articles mentioned at the beginning of this article. For one thing, there is a section titled, "Some Key Passages from the New Testament Where We See the Full Deity and Preexistence of God the Son with God the Father" in the article titled "More on the Trinity.") We desperately need the balanced truth of what the Bible teaches. I am convinced, by the way, that God the Son (and God the Holy Spirit) loves the verses that greatly exalt God the Father.
After we receive the full revelation regarding the Lord Jesus Christ (and the Holy Spirit) through the New Testament, we can clearly see the full deity of the Lord Jesus in the Old Testament, but I don't believe we have to try to see Him typically included when the name Yahweh is used in the Old Testament. I'm quite sure that wasn't God's intention, and it confuses the issue. For one thing, if we overstate the oneness of God based (to some significant extent) on a misinterpretation of Deut. 6:4, we certainly confuse the issue. It's proper to speak of one God, three Persons, but we don't want to overstate that oneness. We desperately need the balanced truth of what the Bible teaches. We also confuse the issue if we don't take seriously what the Bible, very much including the New Testament, says about the subordinate role of God the Son (and the Holy Spirit). Full deity, Yes! Subordinate to God the Father in His role, Yes!