Thank you for the question on the origin of the Mosaic Law, “How do we know that God gave laws to the Israelites rather than the Israelites creating laws based on their own understanding of God?“
As one reads the the Torah or the Pentateuch, the Mosaic Law can’t be separated from the historical setting of the Laws given to the Israelites. The Laws given to the Israelites are in a context. That context is the Exodus and the time at Mount Sinai.
Here are my reasons why it is unlikely that the Israelites created the laws based on their own understanding of God:
A. The belief in a monotheistic God and the worship of a single deity is against the cultural beliefs at that time.
Regardless if one accepts the Exodus or that the Law was written in the 6th in their Babylonian captivity, the cultural practices through the centuries in nearly every culture is a polytheistic view of God. For the Israelites to adopt a monotheistic belief in a God would have defied the beliefs of every people group around them. It would be more likely that they would have adopted some form of the polytheistic religion rather than become a monotheistic religion.
B. The belief in a monotheistic God and the worship of a single deity would have been rejected by most polytheistic Israelites unless there was a transformational reason to become monotheistic. What event or person could have imposed such a religious belief that would change the belief of a people group? If the Exodus is rejected and living among the polytheistic Babylonians, what event would have caused the Israelites to surrender their gods for a single deity? Through Israel history, the Jews strayed to worshiping other deities. That is a natural inclination since they would see all the deities around them.
C. The establishment of Ark and the Tent of Meeting without any idols would have been very foreign to any people group. People draw pictures of their deities and have representation of their deities in their home or in their business. To have no carving or idol of the Israelite’s God would be unreasonable. Nearly every culture has some form of depiction of their deities.
D. The establishment of a theocracy instead of a human dictatorship would be foreign for the Israelites. Every culture from the Egyptians, the Canaanites to the Babylonians had a kingship idea, but for the Israelites, God was to be their king. It was the king who established or modified the laws of the land. If the Laws were given by a human ruler, then another ruler could and would have modified the religious beliefs. The Laws of God transcended any ruler and they were subject to obedience to the Law. If the Laws were considered man-made, then a ruler can change it unless there is a belief that God gave it to them.
E. If the Israelites didn’t believe that the Laws were from God, the Torah would have been corrupted and changed through the centuries. One would think that there would be new laws added to the Torah or laws replacing them according to the ruler. Throughout Israel’s history, the prophets referred to the Laws given by God and rebuked the Israelites for their idolatry. One would think that the Ten Commandments would have accommodated the changing beliefs of the Israelites.The Laws were viewed by the Israelites as being from God, not from man.
F. The dietary laws given in the Law would be objectionable if the Israelites were not in the wilderness for 40 years. If the Israelites were living in Babylon, the prohibition of food would be viewed as unreasonable for who didn’t eat red meat of all sorts of animals and sealife. For the Israelites to suddenly stop eating them would be objectionable. Being in the wilderness, they had limited access to them until they entered the Promised Land. There was a generation who learned to live with the dietary laws before they entered the Promised Land.
The Torah states that the reason the Israelites were to follow such a ceremonial and dietary laws was because they were to be chosen people and a priesthood before the nations. It was to make a distinction between themselves and the surrounding nations. Israel for the most part didn’t follow God’s Laws and became like the nations. It would have been so much easier to change the Laws to accommodate the new environments that they found themselves in whether in the Promised Land or in captivity.
SUMMARY: If the Israelites didn’t believe that the Law came from God himself, they would have changed it. They never did because they believed it comes from God.
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