In Exodus 32:1-6 is an example of what happens when a leader goes away and does not return within the expected time. It provides a clear-cut example of what was happening to the Ephesian church (Revelation 2:4-5).
Moses went up Mount Sinai; Christ went up to Mount Zion in heaven. "What has become of him?" the people asked. "We do not know what has happened to him! He is up there. He is supposed to return, but He has not returned according to our expectations."
What do the Israelites decide to do? They began looking to the world for a solution, in this case to Egypt. In the Ephesians' case, it was the world around Ephesus, the world of Asia Minor. They looked to the culture to gratify them, and they began to drift in that direction.
Moses' return was delayed longer than the people thought that he should have been gone, so their affections pulled their attention elsewhere. The same happened to the Ephesians, only it took a lot longer because of the Spirit of God in them. The people in Exodus did not have the Spirit of God, yet the people in Ephesus—in the church—did have God's Spirit, so what took place very quickly in the book of Exodus was dragged out over a much longer period in the first-century church. The Ephesian's affections were taking them back into the world, and they began to follow the world's ways once again.