“God said to Moses, ‘I am who I am. This is what you are to say to the Israelites: “I am has sent me to you.” ’ ” (Exodus 3:14)
The Israelites were slaves in the land of Egypt, where many gods were worshiped. The Lord wanted his people to know that only one deity was worthy of their worship—only one could free them from captivity.
“I am” is the perfect name for God because it contrasts his existence with the nonexistence of other gods (who might be named “They are not”). It also calls attention to his eternal nature. When nothing else existed, God could say, “I am.” If everything else ceased to exist, God could still say, “I am.”