The Book of Deuteronomy is a series of messages preached by Moses as he seeks to prepare the second generation of Israelites to enter, conquer, and possess the Promised Land. The messages that the book conveys are critically important for God's people at all times.
First, the book was written to teach God's people how to overcome all enemies, trials, and temptations that confront them.
Second, the book was written to stir God's people to rededicate their lives to God, to review their commitment to obey God, and keep the covenant they had made with Him. This chapter deals with the dangers of being seduced into false worship and how God wants us to prevent that.