This sermon is a mashup of Deuteronomy 26:1-11 and Luke 11:24-26. It has the theme of putting things in the right order in our lives. Jesus told a parable of a man that swept his house clean, driving out a single demon. But the man did not fill his now clean house with good things so the demon returned with 7 more demons more wicked than he was.
Similarly, Moses told the Israelites to make sure that they put God first in ordering their lives else they would fall away from him and forgetting how they got their prosperity.
It's the same message. Put first things first or suffer terrible consequences.