The idea of three which are one is taught in the Kaballah .
In the Zohar (the classic text of Kabbalah) and other Jewish sources,
we find that there are three (manifestations of Godliness) which are
essentially One: God, Israel and the Torah. The Zohar states: "Israel,
the Torah and the Holy One Blessed Be He are One." As explained above,
before the contraction, from the perspective of God (and the origin of
the Jewish soul), these three are manifestly revealed as absolutely
One.
It needs to be understood while they recognize the "three-in-one" aspect, they vehemently deny that any one of the three, but God himself may be referred to as an individual.
The non-Jewish attempt to parody this ultimate secret of three which
is One totally destroys the authenticity of the paradox of the
concept. When the consciousness is not one of Atzilut, the "son"
becomes distinct from the Father and the "holy spirit" also becomes
distinct as a personality and the non-Jewish soul falls into idolatry.
This is forbidden for the non-Jew as well as for the Jew. The
prohibition against idolatry is the most important of the Seven
Noahide Commandments.
But notice that Israel as a people is identified as the Son, and their hermeneutic must permit the usage of the singular "He" when referring to Israel as a people. This is done by making Adam Kadmon represent the archetypal soul of Meshiach as a representative of all the souls of Israel.
Three creative forces
The identification of God as three is not limited to the designation above, but also refers to three types of creative force: Power (Energy), Life-Force (Soul), and Light. Please notice the similarity to John's Word 1 which is the 'light' and 'life'.
Three aspects to the Jewish soul
Man was created in the image of God and reflects his triune nature.
Another related manifestation of the three-fold cord is the statement
of the Sages: "On three things the world stands: on Torah, on service,
and on acts of lovingkindness" (Avot 1:2).
This is very similar to the word, works and life triad in referring to the Trinity in SP.
Personification
The many gates of revelation and creative power are personified in Kaballistic writing, and transferred to Jewish myth as divine beings which are lesser than God himself, such as angels. Even the letters of the alphabet are themselves personified, and given personal characteristics such as humility. This is not very different from the personification of the Word as the Son, or Meshiach, or as Adam Kadmon who represents the personification of the Torah itself.
Jewish understanding of Gen 1.26 involves conversations between the personified characteristics of God.
It is a misunderstanding of Christianity to claim that Jesus as the Son of God is a second God, or is divisible from God. Christianity is firmly monotheistic, and marginalizes those who would doctrinally divide the 'persons' of God. There is a closer affinity between Adam Kadmon and Christ, between the Meshiach of the sod and Christ, than to any representation of Christ as a second God.
Trinity
Though written Kaballah did not appear until late, it is claimed that the oral traditions predate the cross. Early formulations of the methods appear around the time of Christ. From his writing it is a plausible claim that John was familiar with the methods of interpretation used.
The idea of a singular God having three aspects is well founded in Kaballah with the idea that they are inseparable. With that, Christians find no argument.
1:
John 1.1-4
We also see the word being associated with power:
Lu 4:32
And they were astonished at his doctrine: for his word was with power.
Lu 4:36 And they were all amazed, and spake among themselves, saying,
What a word is this! for with authority and power he commandeth the
unclean spirits, and they come out.