What is the simplicity of God?
The simplicity of God refers to the fact that, as stated in the Gospels, “God is a spirit” (John 4:24), that is to say, God is bodiless, a simple and therefore uncomposite Being.
With the incarnation of the second person of the Holy Trinity, however, the human nature of Christ - His body and soul - has become forever united in God. The anti-Hesychasts objected to the “essence-energies” distinction (see Question 4 above), because they regarded it as impairing the simplicity of God.
Palamas pointed out that their concern was a philosophical and not a theological one, explaining that the doctrine of the Holy Trinity, that is to say, the threeness of God, did not do violence to the simplicity of God, and nor did the Incarnation of Christ; and so it was also with the “essence-energies” distinction.
The “divine energy” does not constitute a separate entity, for it is in fact God Himself, acting, operating, involved in the life of His creature. The doctrine of the Holy Trinity does not diminish the oneness of God, nor does the “essence-energies” distinction.