Why God Calls the First Age the Age of Law
During the Age of Law, Jehovah laid down many commandments for Moses to pass on to the Israelites who followed him out of Egypt. These commandments were given by Jehovah to the Israelites, and bore no relation to the Egyptians; they were meant to restrain the Israelites. God used the commandments to demand of them. Whether they observed the Sabbath, whether they respected their parents, whether they worshiped idols, and so forth: these were the principles by which they were judged sinful or righteous. Among them, there were some who were stricken by Jehovah’s fire, some who were stoned to death, and some who received Jehovah’s blessing, and this was determined according to whether or not they obeyed these commandments. Those who did not observe the Sabbath would be stoned to death. Those priests who did not observe the Sabbath would be stricken by Jehovah’s fire. Those who did not show respect to their parents would also be stoned to death. This was all commended by Jehovah. Jehovah established His commandments and laws so that, as He led them in their lives, the people would listen to and obey His word and not rebel against Him. He used these laws to keep the newborn human race under control, the better to lay the foundation for His future work. And so, based on the work that Jehovah did, the first age was called the Age of Law.
from “The Work in the Age of Law” in The Word Appears in the Flesh