It is often argued that the Hebrew Bible takes a position not of monotheism, but of henotheism. God reveals himself not as the only god, but rather as the god whom Abraham knows. (Gen 15:7) In such a respect, the god of Israel is not God alone, but the god who was worshipped by Abraham’s clan. In this context, the god of Israel is a type of tribal deity, that although was worshipped alone, did not explicitly exclude the existence of other gods, who were not relevant to them.
In the early Mosaic era, the possibility of other gods is left an open question, although by this stage Israel claims that their god is greater. (Ex 18:11) This same subtle shift is shown in 2 Chr 2:5, and could indicate that Israel understood that the god they recognised was God alone, and other gods were therefore false. This would be Monotheism in the proper sense of the word. By the time of the prophet Isaiah, Monotheism is solidly and explicitly accepted. “Thus says the LORD, the King of Israel and his Redeemer, the LORD of hosts: "I am the first and I am the last; besides me there is no god.” (Is 44:6) Thus, the development of the people of Israel to a true Monotheism, appears to be a gradual process, with the exception of Gen 1:1. It is therefore likely that Gen 1:1 was redacted later than the other examples supplied, and so, the development of Monotheism comes firstly on a tribal level, and gradually advances to recognition that the god of Israel is the only god. It is into this context that Christianity emerges, and thus Christianity was from the outset Monotheistic. (John 1:1)
A strictly literal interpretation of Deuteronomy 4:39 excludes the possibility of henotheism. The verse states: "Know this day, and take it to heart, that the LORD is God in heaven above and on earth below; there is none else." According to the view that Deuteronomy is a late addition to the Five Books of Moses, this would reflect the later adoption of monotheism. However, if Deuteronomy is taken to be part of the original text, as it generally is among those who use it as scripture, this would indicate that the monotheistic concept existed from the time the Torah was composed.
In the west, the Hebrew Bible has been the primary source describing how and when Monotheism was introduced into the Middle East and the west. As believed by followers of some of the Abrahamic religions, it teaches that when Abraham discovered God (Genesis 12:1-9 ; 13:14-18 ; 15 18 ; and 22 ), he thus became the world’s first Monotheist. According to these, until then, in ancient history all cultures believed in a variety of multiple deities such as in idolatry, forces and creatures of nature as in animism, or in celestial bodies as in astrology, but did not know the one and only true god.
However, the Hebrew Bible teaches that, at Creation, Adam and Eve knew God (and so did their descendants) but that over the ages, God and his name were forgotten. This is how one of the most important Jewish sages, Maimonides describes the process in his work the Mishneh Torah:
In the days of Enosh mankind made a huge error…they reasoned that since the Lord created the stars and the heavenly spheres and placed them in the skies giving them great significance, and they serve before Him, it is therefore fitting to praise and elevate them and give them honor believing this to be the Lord’s will to honor that which He makes great and honorable…The people then built altars to worship the stars and to praise and bow down to them…and this was the essence of idol worship (avoda zara)…After a few generations false prophets arose and said that the Lord had actually commanded people to worship the stars…and they built images in their honor…spreading these false images by building them in gathering places, under trees, on tops of hills, and in valleys, gathering people who bowed down to them declaring: ‘Such and such an image brings good or bad luck and therefore fear it’…after a number of generations, the Divine Name was completely forgotten…until the mighty one (Abraham), began to question this in his mind and asked ‘How could it be that the heavenly sphere moves without a Mover behind it? because it is impossible that it moves itself’, and he had no teacher and no-one to inform him for he lived in Ur of the Chaldees surrounded by foolish idol worshippers…He (Abraham) subsequently arose and made it known to the people that there is only one Lord in the entire world and that only He should be worshipped, gathering people from city to city and kingdom to kingdom until he came to the land of Canaan calling out as it says: ‘Abraham planted a tamarisk tree in Beersheba, and there he called in the name of God, Lord of the Universe (El olam) (Genesis 21:33)’ —Maimonides, Mishneh Torah, Sefer Mada ("Book of Knowledge"), Chapter 1, Hilchos Avodah Zarah
written by DRSC