This teaching is a Summary of the Intertestamental Period. 

This allowed us to understand that what we know as the dark ages or silent years wasn't so silent. It was very active and eventful during this period. But it was a dark moment for the people of Israel. God’s people who were supposed to influence the world with the teachings of God were now being influenced by the world. We see this pattern constantly in their history and we see the same pattern for the church. This is why learning about the intertestamental period and the history of the Jews so we can understand their thought and pattern. Oddly enough looking at how religion of Christianity have infiltrated the church, we are repeating the same mistakes of Israel.