If we posit a God beyond the God revealed, then we are left with the worst form of nominalism (I know, I just said the n-word) and skepticism. This is one of the reasons I reject Palamism. There is no such thing as a God-in-itself. Ousias do not have interiorieties.
“For Barth, the triunity of God consists in the fact that God is one Subject in three modes of being. One Subject! To say then that ‘Jesus Christ is the electing God’ is to say, ‘God determined to be God in a second mode of being.’ It lies close to hand to recognize that it is precisely the primal decision of God in election which constitutes the event in which God differentiates himself into three modes of being. Election thus has a certain logical priority even over the triunity of God. [Quoting Eberhard Jüngel:] ‘Jesus Christ is the electing God. In that here one of the three modes of being is determined to be the God who elects, we have to understand God’s primal decision as an event in the being of God which differentiates the modes of God’s being.’ So the event in which God constitutes himself as triune is identical with the event in which he chooses to be God for the human race. Thus the ‘gap’ between ‘the eternal Son’ and ‘Jesus Christ’ is overcome, the distinction between them eliminated…. There is no ‘eternal Son’ if by that is meant a mode of being in God which is not identical with Jesus Christ” (pp. 218-19).
As Ben Meyers summarizes,
The event in which God chooses to be “God for us” is identical with the event in which God “gives himself his own being.” And this event of election is not located in any timeless eternity. God’s eternal decision coincides with the temporal event in which this decision reaches its goal. This coincidence – this event of utter singularity – is God’s being. Time, then, “is not alien to the innermost being of God” (p. 222). The time of Jesus Christ is the time of God’s decision – it is the primal time, the time of God’s eternal movement into history. There is no still-more-primal divine being which lurks behind this movement into history; God’s being is this movement, this effectual decision.