I should preface my comments by saying that since this is an open forum even though what is said may be addressed to specific individuals, it is intended to speak to anyone who may be interested in such things.
Philosophy is about wisdom, not argument.
I agree with Plato - philosophy is the desire to be wise. Fundamental to his search for wisdom is argument. The same holds for Caputo. Both are in agreement that we fall short of the goal, that we are not wise.
Your relating of the relationship is, I take it, a relationship between you and the divine or man and God. In the passage you cite from Caputo he is questioning this relationship. He wishes to extricate himself from:
the onto-theological circuit that circles between being and beings.
We may push against the limits of language but we are still within them. Each of the things you affirm that God is is within those limits and each speaks of the relation that circles between being and beings. Each of those things articulates a concept or idea pertaining to God.
Apophatic theology is an attempt to avoid this, via negativa. But it still operates in the same categories of being and existence.
"The relating is everything: concepts and ideas pertaining to God are all but irrelevant."
All experience is bound, shaped, and determined by concepts and ideas. When you say:
A human being is the relating of a relation — a synthesis of the Infinite and the finite, Eternal and temporal, Freedom and necessity …
You affirm what you wish to deny. These terms, synthesis, Infinite, finite, Eternal, temporal, Freedom, and necessity are the concepts through which you not only relate your experience but through which you experience what you experience. A further sign of you conceptualizing is the use of capitals, signaling a conceptualized ranking in terms of priority, importance, and difference.
We do not first experience and then express what we experience in words. To see is not passive perception, it is active conception. It is “seeing ‘as’”. We do not simply see something, we see it 'as' this or that. The same object may be seen or taken in different ways, depending on the conceptual framework.*
*Kant had the initial insight but saw it in terms of universal categories of the mind. Heidegger and Wittgenstein both saw it in terms of the context of lived experience or a form of life. It is thus not universal but part of our situatedness our being in the world.