‘Being’ is at the heart of Upanishadic testament. As early as 1,000 BCE the terminus of ‘Being’ was well in play.
From the Chandogya Upanishad: ‘In the beginning there was ‘Being’ alone; the One without a second‘.
[What later becomes the ‘Subtle Inner Essence’ of the Upanishad.]
‘Being’ is at the heart of the Bible.
In Exodus, Moses asks The Presence Its name and The Presence replies: Ehyeh Asher Ehyeh.
‘I am that I am…thus you shall say to the children of Israel, I AM has sent me to you‘.
The opening command, the first of the Ten Mosaic Commandments, is a categorical statement of Ontological Presence:
‘I AM the Lord your God who brought you …out of the house of Bondage…thou shalt have no other Gods before Me.’
Of course, Theologians, the intellectuals of the Faith, proceeded to unwrap all this in the only way they knew how.
A reified concept of ‘Being’ was developed extensively first by medieval, later by modern Theologians, which was tagged with a host of sophisticated abstract features: Eternal, Infinite, Omnipotent, Omnipresent, Good-Being, Ground of Being, and such. A list of preferred measurements for Man’s ideal ‘God’.
It kept the language above the common riff-raff who it was thought took the Bible literally.