You asked

how did ancient israelites understand 'heaven' and 'firmament' in contrast to our modern cosmology?

Adds the setting and its conversation across both testaments.

Genesis 1:6-8

“God said, 'Let there be an expanse in the middle of the waters, and let it divide the waters from the waters.' God made the expanse, and divided the waters which were under the expanse from the waters which were above the expanse; and it was so. God called the expanse Heaven. There was evening and there was morning, a second day.”

This passage is from the opening chapter of Genesis, part of the creation narrative. It describes God's work on the second day, establishing a 'firmament' or 'expanse' to separate the primordial waters.

What does understanding ancient cosmologies reveal about how we interpret sacred texts in light of evolving scientific knowledge?

Then — the setting

Ancient Israelites, like their Near Eastern neighbors, likely understood the 'firmament' (רָקִיעַ, *raqia'*) as a solid, dome-like structure, possibly metallic or crystal-like, set above the earth. This dome held back the 'waters above' from raining down chaotically, and had 'windows' or 'floodgates' (Genesis 7:11) through which rain could pass. Their cosmology was a three-tiered universe: Sheol (the underworld), the Earth (a flat disc), and the Heavens (the firmament with celestial bodies, and above it, the dwelling of God). This was a functional, not scientific, description, addressing the order God brought to creation from chaos, rather than precise astronomical details.

Across the Testaments

The Old Testament consistently uses this ancient Near Eastern cosmological framework, describing the heavens as a physical structure where God places the sun, moon, and stars, and from which rain falls. The New Testament, while not explicitly re-describing the firmament, inherits this terminology and worldview. However, its focus shifts from the physical structure to the 'spiritual' heavens as God's dwelling place and the ultimate destination for believers. For example, 'heaven' in the New Testament often refers to the realm of God's presence (e.g., Jesus' ascension to heaven) or the future eternal state ('new heavens and new earth'), rather than primarily the physical sky. The theological meaning of God's sovereignty over creation remains, even as the scientific understanding of the cosmos changes.

Keep thinking

Read alongside it

Psalm 19:1
This verse states, 'The heavens declare the glory of God,' using 'heavens' as a visual testimony to divine power.
Job 37:18
Job describes God as one who 'spread out the sky, which is as solid as a molten mirror,' reflecting the ancient perception of a solid firmament.
2 Peter 3:10-13
This New Testament passage speaks of new heavens and a new earth, showing a theological development beyond the physical structure of the firmament.

Ask your own follow-up