
A depiction of the Critias hypothesis reductionism god disproof, namely the logical progression from polytheism, to monotheism—which in modern terms (Ѻ) equates to belief in personal god, god, spirit, or life force—to zerotheism, i.e. belief in fermions, bosons, and “zero” gods (no gods), as Paul Dirac (1927), below right (Ѻ), saw things.

A depiction of the Critias hypothesis reductionism god disproof, namely the logical progression from polytheism, to monotheism—which in modern terms (Ѻ) equates to belief in personal god, god, spirit, or life force—to zerotheism, i.e. belief in fermions, bosons, and “zero” gods (no gods), as Paul Dirac (1927), below right (Ѻ), saw things.

In atheism, Critias hypothesis (CR:5) is the assertion that gods (and god) are an invention of lawgivers of ancient times, a theoretical tool employed as a kind of overseer of the right and wrong actions of men.

Overview
The Critias hypothesis god reductionism to zero disproof, one of the top ten god disproofs, is the following logic:

Polytheism, i.e. belief in multiple gods, according to Greek philosopher Critias (c.410BC), was an invention of lawgivers of ancient times employed to justify social laws:

“Critias seems to be from the ranks of the atheists when he says that the lawgivers of ancient times invented god as a kind of overseer of the right and wrong actions of men. Their purpose was to prevent anyone from wronging his neighbors secretly, as he would incur the risk of vengeance at the hands of the gods.”
— Sextus Empiricus (c.200AD) (Ѻ)

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Critias reductionism
The Critias hypothesis conjoined to the untenability of polytheism as per the inconsistent logic of having differing governing principles and laws in different provinces, as the universe would see things:

“As I try to discern the origin of that conviction, I seem to find it in a basic notion discovered 2,000 or 3,000 years ago, and enunciated first in the western world by the ancient Hebrews: namely that the universe is governed by a single god, and is not the product of the whims of many gods, each governing its own province according to his own laws. This monotheistic view seems to be the historical foundation for modern science.”
— Melvin Calvin (1969), Chemical Evolution [1]

leads to a method of "god reductionism" to zero gods of sorts; as follows:

Monotheism, i.e. belief in one god, was an invention of lawgivers of ancient times, Egyptian pharaoh Akhenaten (1320BC) in rough draft, arrived at to account for the growing discernment of the conflicting view that differing “regions”, i.e. towns, cities, or states, with their differing gods (lawgivers), seemingly had peculiarly similar “laws”, e.g. stealing was wrong, rocks fell at the same speed, the stars moved similarly, etc.; accordingly, the multiple lawgivers hypothesis seemed to be in error and therefore there must be “one” lawgiver.

“The thought that all the phenomena of motion should follow from one set of principles might seem grandiose and inordinate, but it occurred very naturally to the religious mathematicians of the 17th century. God had designed the universe, and it was to be expected that all phenomena of nature would follow one master plan. One mind designing a universe would almost surely have employed one set of basic principles to govern related phenomena.”
— Morris Kline (1982), Mathematics: the Loss of Certainty; on Newton attempting to reconcile Galileo’s laws of terrestrial motions and Kepler’s laws of celestial motions (Ѻ)(Ѻ)

Atheism, i.e. belief in zero gods, was initiated, predominantly by Goethe (1796), when it was realized that if the laws governing the social realm were similar, if not the same, as the laws governing the chemical “realm”, the realm where there was NO god, but only strict determinism, then there must be, therefore, no god.

The theory of “multiple gods”, according to the Critias hypothesis, to elaborate, arose per the logic that each town, of ancient times, beyond 150 in size (see: Dunbar model morality, §6 below), needed “laws” to regulate unruly behavior, therefore there had to be conceptualized “lawgiver” (possibly akin to the way we think presently as Newton being the lawgiver of the laws of motion, so to say); subsequently, each town of ancient times invented their own special unique town or city god as the deemed lawgiver, with its own unique properties.

As science (knowledge) progressed, however, thinkers began to find that certain laws, e.g. gravity, the movement of the stars, or the tides, etc., were the same in each town, therefore the “multiple lawgivers hypothesis” became suspect and problematic, i.e. there had to be ONE lawgiver [god] for all of the towns, because the measurement of “laws” in each town, e.g. rate of acceleration when a stone is dropped, were found to be uniform; after which "monotheism" was invented as the upgrade solution to multiple gods = multiple laws problem. The upgrade from monotheism to atheism, like the former historical transition, is presently underway, as the solution to the “multiple monotheistic gods = multiple monotheistic laws” problem; particularly when it comes to questions of morality, e.g. Quranic morality vs Biblical morality vs Hindu morality (although this, technically, is polytheistic; approximately), when the sciences, e.g. neuroscience (e.g. Greene), physical chemistry (e.g. Goethe), and chemical thermodynamics (e.g. Rossini), are beginning to show one set of moral laws in each land, the same way as the stone drops at the same rate in each land.

References
1. Calvin, Melvin. (1969). Chemical Evolution: Molecular Evolution towards the Origin of Living Systems on the Earth and Elsewhere (pg. 258). Clarendon Press.