The question is really an issue of what kind of cosmology the authors of the various biblical books assume in the course of their writing. When we read the Hebrew scriptures, the few books that have anything to say on the subject never explicitly say 'the earth is flat'. But if we can determine the overall shape of the cosmos as the different writers describe it, we'll be able to know if a 'flat earth' is an accurate label for what the ancient biblical authors believed.
The main biblical texts that describe the cosmos as a whole are Genesis 1, Psalm 74.12-17, Psalm 104, Job 26.5-14, Job 37, Job 38, Proverbs 3.19-20, and Proverbs 8.22-36, along with a few pieces here and there where a particular cosmology is assumed by the writer.
The primeval waters
Ancient Israelite cosmology begins with a mess of waters, representing the pre-creation chaos. The world is created inside of this chaotic sea. These primeval waters are found in:
- Genesis 1.2,6-7,9,etc., as 'the deep' and 'the waters', so that the earth was created between 'the waters above' and 'the waters below' when God spoke it so
- Psalm 74.13, as 'the sea' and 'the waters' (and metaphorically as 'the sea monsters' and 'leviathan'), which God 'divided', 'broke', and 'crushed' as the first act of creation
- Psalm 104.3,6-9, as 'the waters' and 'the deep', which uncovered the earth when God spoke it so
- Job 26.8,12, as 'the waters' and 'the sea' (and metaphorically as 'Rahab' the sea 'serpent'), which God 'binds up', 'stilled', 'shattered', and 'pierced'
- Job 38.8-11, as 'the sea' with its 'proud waves', which God 'prescribed limits' so that it would 'come no farther' over the earth
- Proverbs 3.19-20, as 'the deep', which God 'broke open' when he 'founded the earth'
- Proverbs 8.27-29, as 'the deep' and 'the sea', upon which God 'drew a circle' (more below on this 'circle'), and was 'assigned a limit' when God spoke it so
Within the primeval waters, God creates a solid dome called (in English) 'the firmament'. This crystalline structure is sometimes compared to sapphire, explaining the blue color of the sky. While some English translations use an ambiguous word like 'expanse' or 'canopy' to make the concept more friendly to modern science, which presents a comparatively 'soft' atmosphere around the earth, the biblical authors consistently portray this firmament as solid. This firmament is found in:
- Genesis 1.6-8, where it is given the name 'Heaven', where its express purpose is to 'separate the waters [above] from the waters [below]'; the Hebrew word used is raqiya, drawn from a verb regularly used to describe striking or pounding on an object; the sense is of an object that has been 'pounded' into its present shape
- Job 37.18, where it is called 'the sky', and is 'spread out' (the verb root of raqiya), and is described as 'hard as a molten mirror'
- Proverbs 8.28, where God 'made firm the sky above'
Numerous passages in the bible describe heaven as a scroll or tent that is 'stretched', or may 'collapse'. The sun, moon, and stars were placed in/on the firmament, and moved upon its surface (e.g. Genesis 1.14-19; Joshua 10.13; Daniel 12.3). The firmament rested upon the mountains/pillars (e.g. Job 26.11), and heaven (as in, God's domain) was conceptualized as resting just above the firmament:
- Exodus 24.1-2,9-11 shows us Moses and the elders of Israel invited by God to the top of Mount Sinai, whereupon 'they saw the God of Israel'; the narrator describes the firmament as 'a pavement of sapphire stone, like the very clearness of heaven'
- Ezekiel 1.22-28 and 10.1 has the prophet see a vision of the glory of God in heaven, where he describes the firmament as 'shining like a dreadful crystal', above which was 'the likeness of a throne, in appearance like sapphire'
- (Revelation 4.6 draws on Ezekiel, describing the firmament as 'a sea of glass, like crystal')
Weather functions are executed through openings that are fixed upon the firmament:
- Genesis 7.11, 8.2, Second Kings 7.2,19, Isaiah 24.18, and Malachi 3.10 describe heaven / the firmament as having 'windows' through which 'the waters above' fall as rain, and most significantly as a world-ending flood
- Job 37.6,9-12,15-17 describes the weather functions as executed upon God's command, while Job 38.22,35,37 specifies that snow, wind, and rain are found in heavenly 'storehouses' and 'waterskins', with Job 38.28-30 showing their ultimate origin is 'the deep' found above heaven / the firmament
The earth is then created inside of the primeval waters, underneath the protection of the firmament.
- Genesis 1.9-10 has 'dry land' created upon 'the waters under the heavens'
- Psalm 104.5, where God sets 'the earth' on its 'foundations' (i.e. 'pillars', as in Psalm 75.3) and removes the covering of the deep, so that 'the mountains rose' and 'the valleys sank down'
- Job 26.7,10, where God 'suspends the earth over nothing' and 'inscribed a circle on the face of the waters'
- Job 38.4, where God 'laid the foundation of the earth'
- Proverbs 3.19-20, where God 'founded the earth'
- Proverbs 8.27, where God 'drew a circle on the face of the deep'
Two verses above describe a 'circle' being 'drawn' on the surface of the deep (Job 26.10, Proverbs 8.27). The only other time this specific Hebrew word 'circle' is used outside of these two verses is in Isaiah 40.22, where it describes 'the circle of the earth'. However, a closely related word is used in Isaiah 44.13, where it is often translated as 'compass'. The word 'circle' in the three verses does not describe a sphere, it describes a round, disc-like shape.
To recap the above: the earth was a disc-like mass that rested on 'the water below', and was contained underneath a crystalline dome, which in turn held back 'the waters above'. While none of the biblical texts describe the act of creation in exactly the same way or shape, they are in general agreement and complement each other quite well. The final picture we are left with is something similar to this:1
This is remarkably similar to the cosmology of other Ancient Near Eastern cultures contemporary to the biblical authors. For a deeper exploration of the similarities between ancient Israelite cosmology and the cosmology of neighboring cultures, I highly recommend the book The Lost World of Genesis One by John H. Walton.
While we should definitely take the time to lend some nuance to the phrase, the Hebrew scriptures certainly describe a 'flat earth'.
1 I am the creator of this illustration. Subject to CC BY-NC.