In the intervening years, from the time that Levi came into Egypt with his father Jacob, the Israelites had forgotten about God. They had given up their monotheism, their worship of the God of Abraham, Isaac, and Jacob. Instead, they had copied the people of the land and began worshipping the gods of Egypt (their progenitors had also done so in other lands). Regarding this same period of time, Ezekiel says:
Say to them, "Thus says the Lord GOD: 'On the day when I chose Israel and raised My hand in an oath to the descendants of the house of Jacob, and made Myself known to them. . . .'" (Ezekiel 20:5)
Remember this phrase, "made Myself known to them." Had they forgotten Him in Egypt? Yes, they had. They did not know God any longer. Just a few did, like Amram and Jochebed, who retained the religion, the worship of God.
"'...and made Myself known to them in the land of Egypt, I raised [lifted] My hand in an oath to them, saying, "I am the LORD your God." On that day I raised [lifted] My hand in an oath to them, to bring them out of the land of Egypt into a land that I had searched out for them, "flowing with milk and honey," the glory of all lands. Then I said to them, "Each of you, throw away the abominations which are before his eyes, and do not defile yourselves with the idols of Egypt. I am the LORD your God." But they rebelled against Me and would not obey Me. They did not all cast away the abominations which were before their eyes, nor did they forsake the idols of Egypt. Then I said, "I will pour out My fury on them and fulfill My anger against them in the midst of the land of Egypt."'" (Ezekiel 20:5-8)
The Sabbath was forgotten. We know that circumcision was also forgotten because of what happened in the wilderness and when Joshua took them into the land. In the wilderness, they had to circumcise the men. Why were not they already circumcised? Because they had forgotten the covenant that God had made with Abraham, Isaac, and Jacob. Instead, they adopted the religions of Egypt and were worshipping false gods and participating in heathen festivals.
John W. Ritenbaugh
Conviction and Moses