The energies of God doctrine provide an understanding of how God sustains His creation; it is absurd to say they at not nothing or whatever. The beginning is when God (the Word) creates all there is. Since this encapsulates time and space, we would argue that the beginning is just that, a beginning of time and the rest.
The notion of nothing is required by how we use language - since there is a beginning, there cannot be something prior to that. Also the creation is a gift (it is not necessary) from God, and our capacity to comprehend it, study, provide scientific insights, also speak to our place within the Creation.
I cannot make sense of some of your statements concenring rationality, eternity and what have you. 