Leviathan and Rahab
Whether the sea monsters of the psalms and Job are creatures of the created order or echoes of an older chaos-conflict myth.
Psalm 74:12-17
12Yet God is my King of old, working salvation throughout the earth.
13You divided the sea by your strength. You broke the heads of the sea monsters in the waters.
14You broke the heads of Leviathan in pieces. You gave him as food to people and desert creatures.
15You opened up spring and stream. You dried up mighty rivers.
16The day is yours, the night is also yours. You have prepared the light and the sun.
17You have set all the boundaries of the earth. You have made summer and winter.
What each tradition says
Rabbinic / Midrashic
Gunkel suggests that Behemoth and Leviathan were two primeval monsters. They correspond to Tiamat, meaning “the abyss” (compare Hebrew “tehom”), and Kingu, meaning Aramaic “’akna,” or serpent, in Babylonian mythology.
Emil G. Hirsch, Kaufmann Kohler, Solomon Schechter, Isaac Broydé, The Jewish Encyclopedia (New York: Funk & Wagnalls, 1901-1906), vol. 8, s.v. 'Leviathan and Behemoth' — article 'Leviathan and Behemoth', section 'In Apocryphal Literature'
Patristic
Augustine says of the dragon, “There is that dragon which Thou hast made to be a sport therein.” The source presents the dragon as something God made, existing as a sport in that place.
Catholic
No sourced position found. Checked New Advent: the Catholic Encyclopedia 'Job' article (no leviathan/behemoth treatment), 'Psalms' and 'Dragon' articles (no sea-monster note), and the Summa (I.65 on the creation of bodies: no leviathan); bibliaplus Haydock commentary on Psalm 74 (not hosted); archive.org Aquinas commentary on Job (PDF only, no djvu text layer) — no citable statement on the chaos-conflict reading found.
Orthodox
No sourced position found. Checked John of Damascus, An Exact Exposition (Book II ch. 5-7 on the visible creation and the sea: no leviathan/rahab treatment; the word does not occur in NPNF ser. 2 vol. 9), the NPNF ser. 2 vol. 14 patristic catenae, pravoslavieto.com Philaret and the Synod of Jerusalem 1899 — no statement on Ps. lxxiv. 12-17 or Job xl-xli found.
Reformed / Protestant
Calvin takes Leviathan metaphorically for Pharaoh and his army. He says this expression is common among the prophets, especially for the Egyptians, whose country was washed by a sea and divided by the Nile. Pharaoh is not improperly called Leviathan because of his land's sea advantages and his splendid reign, like a whale moving at ease in the ocean.
John Calvin (1509-1564), Commentary on the Book of Psalms, vol. 3 (trans. James Anderson; Edinburgh: Calvin Translation Society, 1849) — Commentary on Psalm 74:13-14 ('Thou hast broken the head of Leviathan in pieces')
Evangelical
No sourced position found. Checked CCEL: Wesley's Notes (no notes on the psalter in the CCEL set), Matthew Henry's commentary pages (JS-only shells, no served text), Barnes' Notes (New Testament only); bibliaplus' Adam Clarke commentary (Psalms not hosted); Project Gutenberg for a PD evangelical psalm commentary — no statement on Ps. lxxiv. 12-17 found.