What role did God intend for Israel according to Exodus 19?

Exodus 19 declares God's intention to make Israel a kingdom of priests and a holy nation. He placed them under law to prepare them for that tremendous role, so they could bring all the nations of the world to a knowledge of their God.

Les explains that Exodus 19 says, "I will make of you a kingdom of priests, a holy nation." He maintains God put them under law to prepare them for that tremendous role, which would have been theirs to carry out. When the opportunity came, they could have had the king and the kingdom and could have brought all the nations of the world to a knowledge of their God. Instead, in unbelief they rejected the king and the kingdom, were dispersed, lost their temple and worship, and God turned to the Gentiles without using the nation of Israel. Later, the 144,000 Jews will get a taste of what the nation as a whole missed.

Exodus 19

What did Israel have to do to become a treasured nation above all other nations in Exodus 19?

Israel had to be obedient to God's covenants. In Exodus 19, God said that if they would obey, they could become a treasure above all the other nations of the world, because the earth is His. He also called them to be a kingdom of priests and a holy, set-apart nation.