ineffable — in·ef·fa·ble — /inˈefəb(ə)l/
adjective: too great or extreme to be expressed or described in words.

Google dictionary

There is a long, but little known, tradition of what is known as an apophatic view of God in Christian thought, especially in Eastern Orthodox theology. In this view, God cannot be understood in words, and therefore the only way to use words to describe God is to list all the things God isn’t. Thus, we have explanations like the following:

We therefore maintain that [God] is neither without being nor without life, nor without reason or intelligence; nor is it a body, nor has it form or shape, quality, quantity or weight; nor has it any localized, visible or tangible existence; it is not sensible or perceptible; nor is it subject to any disorder or inordination nor influenced by any earthly passion; neither is it rendered impotent through the effects of material causes and events; it needs no light; it suffers no change, corruption, division, privation or flux; none of these things can either be identified with or attributed unto it.

Mystical Theology Chapter IV
Dionysius the Areopagite

Dionysius is usually considered to be in the line of Neo-Platonism, which is a combination of the philosophy of Plato and what is likely to have been heavily eastern-influenced mystical religions. Although I have not seen any references which draw a direct connection to far eastern religions, one cannot read the quote above without bringing to mind this well-known quote from Taoism:

Look, it cannot be seen – it is beyond form.
Listen, it cannot be heard – it is beyond sound.
Grasp, it cannot be held – it is intangible.
These three are indefinable;
Therefore they are joined in one.
From above it is not bright;
From below it is not dark:
An unbroken thread beyond description.
It returns to nothingness.
The form of the formless,
The image of the imageless,
It is called indefinable and beyond imagination.
Stand before it and there is no beginning.
Follow it and there is no end.
Stay with the ancient Tao,
Move with the present.
Knowing the ancient beginning is the essence of Tao.

Lao Tzu, Tao Te Ching (Feng & English trans.)

The notion that the primary-ground-of-the-universe is ineffable goes back at least 3000 years. Human language, while very powerful, cannot – by definition – explain or describe God.

If you have a notion of God, set it aside!