The problem is that, if I was to achieve theosis, unity with God, at the moment I was united with God, participating in His essence and nature, God would no longer be Trinity, but rather a God of as many hypostases as people participating in his essence?

So, if I were to believe both doctrines of theosis and Trinity, I would have to recognise that in God there are further distinctions apart from between the Trinity; there is that part of God which is accessible to us, and that part of God which is inaccessible. That with which we can have union, and that with which we cannot.

Lossky in his fourth chapter of Mystical Theology of the Eastern Church, turns to this conundrum, and separates God into his essence and persons, which are ‘totally inaccessible, unknowable, and incommunicable’, and his energies, through which he ‘manifests, communicates, and gives of Himself’. To break it down:

The Energies are ineffably distinct from the Essence. This distinction is how the Trinity can remain incommunicable but at the same time come and dwell within us. The union to which we are called is neither hypostatic (as in Christs’ human nature) or in the sharing of substance (as in the Trinity), but through His energies, and therefore without our essence becoming thereby the essence of God. Hence, in deification we are (by grace or in the divine energies) all that God is by nature, save by his substance (His identity of nature).

Why must God remain inaccessible, or incommunicable? Well, Etienne Gilson expresses the principle: “Lower even if only for an instant and at a single point, the barrier between God and man which is created by the contingency of being, and you have deprived the Christian mystic of his God, and thus of his mysticism itself.” That is to say, to allow God to be accessible or communicable, would be to allow a God that could be understood and accessed by our own minds and our knowledge; for us to surpass that, to become deified, requires a goal (and a God) that is beyond our understanding.

It is important also to identify the barrier Gilson mentions as created by the contingency of being, as opposed to the revelation I’ve discussed previously: The barrier is between the created and the creator, and definitive, rather than between the revealer and the revealed, and intentional.

So to finish, a summary by St Maximus, less thorough, but more poetic: “God has created us in order that we may become partakers of the divine nature, in order that we may enter into eternity, and that we may appear like unto Him, being deified by that grace out of which all things exist have come, and which brings into existence everything that before had no existence.”