The English word ''god''
The English word “god” came from German “gott” which came from Proto-Germanic “guda” which came from Proto-Indo-European “ghutos” (“ghew” - pour/libate + “tos”). Thus, etymologically speaking “god” refers to a liquid offering being poured probably onto a dead body (as in a religious ritual expressing belief in the after life /ancestor worship ). Later, when the concept of personal gods occurred, instead of calling the offerings “god”, they called the divine person who receives the offerings “god”.
Both the Greek word theos and English word god does not originally refer to a personal deity but to either a holy place or the offering itself. These things (sacred place and offerings) are both associated with the concept of personal deities. However, according to history, the most primitive religious belief is Animism ( the belief that all physical things are alive because they have spirit in them) and the belief that the soul or spirit (life force) does not die so that ancestral worship (honouring dead humans ) was the first ever religious worship in history. This explains why burial rituals were the first religious activities. The concept of personal deities came much later.
The lack of personal deities in the most ancient human societies explains why “god” in its etymology does not have the meaning of “a personal god”. “god” in its original and most ancient sense is about a holy place (burial site) or the offering (burial ritual) made to honour dead human bodies due to the belief that they are not really dead but are continually alive in their souls. This belief in immortal souls is because of the universal belief in “Animism” that every physical thing (trees, stones, human bodies, water, mountain etc.) are all alive because they all have spirits.
Summary
The English word “god” (proto-Indo-European “ghutos”) originally refers to the (liquid) offerings being poured onto the dead in burial practises. When the concept of personal deities arose, they re-use and applied the word to divine persons. “god” in the language of Babylonians originally refers to a “priest”. “god” in the language of the Akkadians, Arabic , Aramaic and Latin were all originally referring to the “sky” or “heaven”. When people started to worship celestial objects (sun, moon and stars - all are found “in the sky” or “heaven”) and began treating them as persons, they simply called them “gods” which means that the personal deities are called “gods” simply because they are recognised as persons whose dwelling place is in the sky (heaven).
The Greek word 'theos'
The Greek word theos came from Proto-Hellenic t’ehos which came from Proto-Indo-European word dehs (sacred place) from deh (to put) [1]. Thus, theos refers to a holy place (probably an altar or a temple) where sacrifices are put or offered. Based on its etymology, theos does not specifically refer to a deity [2] at all but is highly associated with a priest (the one who puts sacrifices or does an offering in a holy place). It could be also associated to a more primitive societies like that of the hunter gatherers [3] (who were animists) so that the sacred place refers to the burial place/site where they put their dead and do their rituals.
The Greek word “theos” (Proto-Indo-European “dhes”) originally refers to a sacred place (either a temple where priests put their sacrifices or a burial place where the dead humans are put in order to honour them).
Notes
[1] https://en.wiktionary.org/wiki/%CE%B8%CE%B5%CF%8C%CF%82
[2] The Latin fēriae (''festival days'')also came from the same Proto-Indo-European word dehs (sacred place) from deh (to put). Consistent with the Greek, the Latin also does not refers to a personal deity, but something related to it like fānum (“temple”).
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4958132/
The Hebrew word ''El'' (pl. ''Elohim'')
''El'' came from two Hebrew letters Aleph (appearing as the head of an ox in pictographs, indicating strength of an ox) and Lamed (which appears as the staff of a shepherd in pictographs, indicating authority of a shepherd). Thus, El refers to one who is both strong and has authority to rule others. Based on its etymology, El accurately means a “strong leader”.
The plural of El is Elohiym (“strong leaders” refers to the “judges” in Israel or the “angels” who function as “princes” in the divine council). The Elohiym as ‘intensive plural’ used for the singular subject means “the strongest one”, “one with all powers/ strength (the almighty)”.
Both Yahweh and the Israelite king were called Elohiym in the intensified plural to indicate they have all power in the nation of Israel. Moses too was called Elohiym in the intensified plural to indicate he had all power over Pharaoh (who had all power over all Egypt). This shows that the Hebrew El corresponds to Kyrios in Greek since they both have the denotation of being superior or supreme as leaders (having all power/authority above all others). This is also why in English “god” is defined as “the supreme being”. Therefore, when seen in light of their inherent meaning in Hebrew and Greek, the English lord and god are actually synonymous.
Summary
The Hebrew word “El” originally refers to a “strong leader”. Thus, it is applied to Yahweh, the judges in Israel, the prophet Moses, the Israelite kings, the angels who function as princes over all nations. Its intensive plural “Elohiym” means “almighty leader” which is usually the sense being applied to Yahweh in the Bible. The Hebrew word El (supreme being) is synonymous with the Greek word kyrios (superior). Both El and kyrios equally carry a functional sense.
Notes
El in Proto-Semitic is Il which came from the Old Babylonian word “Ilum” ( priest). Its cognate in Akkadian is “Ilu”. Arabic “Ilah” and Aramaic “Alah”.
