Trinity in Kabbalistic Writings

DISCLAIMER:  I'm citing this just to show that traditional books of Rabbinic Judaism support the idea of the Trinity;  I'm expressly not supporting the Zohar.

"Come and see the mystery of the word [Adonai]: there are three steps, each existing by itself: nevertheless they are One, and so united that one cannot be separated from the other. The Ancient Holy One is revealed with three heads, which are united into one, and that head is three exalted. The Ancient One is described as being three: because the other lights emanating from him are included in the three. But how can three names be one? Are they really one because we call them one? How three can be one can only be known through the revelation of the Holy Spirit ." (Zohar, Vol III, 288; Vol II, 43, Hebrew editions)  [from:  http://www.messiahnj.org/af-tri-unity.htm]

Hear, O Israel, Adonai Eloheinu Adonai is one. These three are one. How can the three Names be one? Only through the perception of faith: in the vision of the Holy Spirit, in the beholding of the hidden eye alone! The mystery of the audible voice is similar to this, for though it is one yet it consists of three elements-fire, air and water, which have, however, become one in the mystery of the voice. Even so it is with the mystery of the threefold Divine manifestations designated by Adonai Eloheinu Adonai - three modes which yet form one unity. This is the significance of the voice which man produces in the act of unification, when his intent is to unify all, from the Infinite (Ein Sof) to the end of creation. This is the daily unification, the secret of which has been revealed in the holy spirit," (Quoted from Zohar II, 53b, as excerpted from Studies in Zohar by Yehuda Liebes)