The bedrock of normative Judaism has always been strict monotheism—the belief that there is numerically only one God, the God of Israel, whose name is YHWH, usually written as “Yahweh.” This belief in one God is what made a Jew a Jew. It distinguished Jews from their neighbors, who during antiquity were polytheistic.
Jews have always believed that their faith is expressed so resolutely in what they call “the Shema.” Recorded in their scriptures, it reads, “Hear, O Israel! The Lord is our God, the Lord is one! And you shall love the Lord your God with all your heart and with all your soul and with all your might” (Deuteronomy 6.4-5 NASB).
The Hebrew word that is translated “one” in Deuteronomy 6.4 is echad. Its primary meaning is the numeral “one,” and it is so translated over 600 times in the New American Standard Bible (NASB). The second most prominent translation of echad in the NASB is the word “each,” which is so translated fifty-five times. So, echad usually means numerically “one.” Context is the primary determining factor.
Jesus repeatedly endorsed the Shema. Like any other Jew, he seemed to believe that God was numerically one. For example, a scribe once asked him, “What commandment is the foremost of all?” (Mark 12.28; cf. Matthew 22.36). Jesus answered by quoting the Shema, saying it was “foremost” (Mark 12.29). The scribe replied, “Right, Teacher, You have truly stated that he is one; and there is no one else besides him” (v. 32). Jesus accepted this as correct by replying, “You are not far from the kingdom of God” (v. 34). Did Jesus mean that God was one person and not two or three? It seems that he did because that’s what the scribe meant.
On another occasion, the Johannine Jesus even more precisely identified God as numerically one. Jesus said to his accusers, “How can you believe, when you receive glory from one another and you do not seek the glory that is from the one and only God?” (John 5.44). Later, Jesus prayed to the “Father” on behalf of his disciples, “This is eternal life, that they may know You, the only true God, and Jesus Christ whom You have sent” (17.1, 3). So, Jesus not only described the Father as “the one and only God” and “the only true God,” but he distinguished himself in doing so. This represents a clear denial by Jesus that he himself is God.
Trinitarian scholars insist that they are monotheistic, thus believing in one God. But most of them define “one,” here, as a unity rather than numerically. Many Muslims and Jews, who also claim to be monotheistic, reject this definition, contending that monotheism means belief in numerically one God, who is a single person. Thus, they allege that Trinitarianism is tritheistic, meaning belief in three gods.
So, how did we get this word monotheism? Henry More, a Cambridge Platonist philosopher, coined the word “monotheism” in the 17th century. It represents a transliterated conjoining of two Greek words. The word “mono” derives from the Greek word monos, meaning “only,” “alone,” or “single.” But as a prefix, “mono” can also mean numerically “one.” The word “theistic” derives from theos, the Greek word for “god.” So, theism means “belief in god.” Joining these two words together signifies belief in numerically one god/God in contrast to the word polytheism, which means “belief in many gods” or “more than one god.” Yet Trinitarians define the one God of the Bible as three co-equal Persons. It seems questionable that Trinitarian Christianity can be categorized as monotheistic. That’s why some modern scholars reject the word “monotheism” as a useful category.
However, in Jesus’ phrase quoted above–calling the Father “the only true God” (John 17.3)–this phrase in the Greek text is monon alethinon theon. Remove alethinon (true) from it, and we have a biblical basis for the word “monotheism.”
Jews have vehemently defended their monotheism against Trinitarianism. And they have denied any hint of Trinitarianism in their scriptures. For many religious Jews, the church doctrine of the Trinity seems blasphemous, and this is surely how Jews would have viewed it during the time of Jesus. Raymond E. Brown rightly says of that era, “For the Jew ‘God’ meant God the Father in heaven.” (The Qur’an repeatedly rejects the doctrine of the Trinity as blasphemous.)
The main thing that has divided Christians and religious Jews has not been whether or not Jesus is the Messiah, but whether the one God consists of more than one Person. Jewish writer David Klinghoffer rightly explains, “In Talmudic and other early rabbinic literature [produced during the early centuries of the Christian era], the most often heard polemical theme directed against Christians has to do with the charge that the latter worshipped two gods. Not three, as in later Christian formulations—the Father, Son, and Holy Spirit—but two. In the first centuries of our era, not all Christians had yet become formal Trinitarians, for the Holy Spirit had not yet joined the pantheon.”
Then, how should monotheism be defined? Larry Hurtado suggests that, despite anomalies, we should “take people as monotheist if that is how they describe themselves.” But most Christians don’t allow such a loose definition for confessional conversion to their faith. Most church denominations have established some criteria for deciding who is a genuine Christian (though they often disagree on the criteria). In fact, this usually is reflected in their requirements for formal church membership.
Thus, Christians generally do not accept a person as one of their own merely because that person professes to be a Christian. Rather, prospective converts must meet the established criteria of that particular church community. In times past, such standards often have been set forth in the form of a catechism or a creed. The New Testament (NT) reveals that the early Jewish Christians required at least the following confessional criteria: Jesus is Messiah, Savior, and Lord, and God proved it by raising him from the dead (Romans 10.9-10; John 20.30-31; 1 Corinthians 15.3-4).
Likewise, it seems there could be some criteria for determining who is a monotheist and who is not which would go beyond mere profession. I suggest as a simple formula the etymology of “monotheism” set forth above, a definition which is in sharp contrast to “polytheism.” And that is indeed what characterized ancient Judaism from the religions of its neighbors: Jews worshipped numerically one God whereas their neighbors worshipped many gods. Accordingly, it is very doubtful that either Binitarianism, which is belief in two Persons in one Godhead, or Trinitarianism, which is belief in three Persons in one Godhead, can rightly be categorized as monotheistic.
(See a list of over fifty, two-three page posts on why the Bible does not say Jesus is God by clicking here.)