Occam's razor favors the simplest answer. Old Testament authors believed and wrote that the earth is fixed. The simple explanation makes sense because people living in that region at that time didn't know the earth moves. 
1 Chronicles 16:30: "He has fixed the earth firm, immovable." 
Psalm 93:1: "Thou hast fixed the earth immovable and firm ..." 
Psalm 96:10: "He has fixed the earth firm, immovable ..." 
1 Chronicles 16:30: Fear before him, all the earth: the world also shall be stable, that it be not moved.
The Bible and science
- The Bible doesn't say the earth orbits and rotates in ways that humans can't change.
- The Bible says the earth has firm foundations and isn't moving.
There is clear scientific evidence for mistakes in the Bible.  Believers try to rescue the Bible but this involves complex unprovable assumptions. Remember Occam's razor tells us we should prefer simple explanations with few assumptions rather than complex explanations with many assumptions.
- Believers must assume the Bible is divinely inspired while other supposed sacred texts from other religions that contradict the Bible are false Superstition. There is no reason to treat the Bible differently from other supposed sacred texts.
- Believers must assume the inspiring Deity chose ambiguous language open to misinterpretation. Especially before Heliocentrism came to be widely known the Bible seemed to show a fixed earth. Why should a deity go to the trouble of inspiring a sacred text and leave the language unclear?
Believers end up with complex explanations for the way the Bible describes a fixed earth  and this shouldn't surprise us. These explanations are less plausible.
- As we showed above the Bronze Age and Iron Age people who wrote the Old Testament didn't know the earth moves and the simplest explanation is that they wrote what they mistakenly believed.
- The simple explanation is plausible because people living in that region at that time didn't know the earth moves.
- The simplest explanation is that the Bible is mythology similar to other Mythology of the time and that the Bible is untrue.
One thing that's really hard to explain is why in the 21st century so many people still take seriously texts written by Bronze Age and Iron Age people who didn't even understand the dynamics of the Solar system.
References and footnotes
- Ancient Greek astronomer, Aristarchus of Samos proposed a Heliocentric theory but he lived in a different area and well after most of the Old Testament was written. Historians know of no earlier heliocentric theories than the theory of Aristarchus. In any case Aristarchus didn't have much of a following and heliocentrism didn't become popular till Copernicus, Galileo, and Kepler made their discoveries roughly two millennia later.
- See Scientific, Historical Errors & Mistakes in the Bible for yet more reasons to be skeptical about the Bible that don't involve Geocentrism.