Upvote:1
It seems to me that before the Enlightenment, the predominant understanding of the structure of the universe was that the cosmos, while stratified, is unitary- that "the Heavens", which include the spheres of the stars, then of the angels, and the abode of YHWH, have substantial existence in the same way that the Earth does.
When one speaks of Christian beliefs, one must recall that the beliefs which developed in the west - particularly in the medieval period, perhaps beginning with Charlemagne - were in some cases radically different from the beliefs held by the eastern Christians that now, for the most part, form the Orthodox Church.
I don't think any of the Church Fathers had a belief that the abode of God and His angels had any kind of "substantial" existence.
John of Damascus (8th century) explained:
The heaven [sic] is the circumference of things created, both visible and invisible. For within its boundary are included and marked off both the mental faculties of angels and all the world of sense. But the Deity alone is uncircumscribed, filling all things, and surrounding all things, and hounding all things, for He is above all things, and has created all things.
For the great part the heaven is greater than the earth, but we need not investigate the essence of heaven, for it is quite beyond our knowledge.
-- An Exact Exposition of the Orthodox Faith, Book III