In Egypt before Pharaoh had released them, on the way out of Egypt when Pharaoh had changed his mind, and over and over in the wilderness, these people have personally witnessed saving acts of the Lord.
Moses is not around at the moment. Without him, they seem to think God is gone, as well. "Let's make some gods for ourselves," they say to Aaron. We are not told what Aaron thinks or what Aaron fears, but we are told that he complies with their wish. Or does he?
When he formed the golden calf and built an altar, he then proclaimed that the festival would be to the Lord. What was he thinking?
How easy or difficult is it for us to distinguish between what looks like Lord-worship and what is actually something-else-worship?
Who or what is Moses to us?
What substitutes are necessary?
Are we capable of remembering what God has already done for us?