This verse is often misinterpreted as describing a solid, dome-like firmament literally holding back a massive ocean of water above a flat earth, echoing ancient cosmologies but clashing with scientific understanding of the atmosphere; in reality, it employs phenomenological language from the ancient perspective, where the sky appears as a vault separating earthly waters from the 'waters above' perceived in rain or clouds, not prescribing a specific physical structure.
Genesis 1:7
King James Version (1769)
7 And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament: and it was so.
On the second day of creation, God forms the firmament, or expanse of the sky, to separate the waters below it—such as seas and oceans—from the waters above it, like clouds or atmospheric vapor, showcasing His divine authority to impose order on the primordial chaos and lay the foundation for a habitable world.