What does it mean that Israel was God's peculiar treasure?
Being God's peculiar treasure meant Israel was set apart above all peoples in covenant relationship with Him. If they obeyed His voice and kept His covenant, God lifted them out of the mainstream of humanity as His favored, chosen people, preparing them for a future role amid surrounding pagan idolatry.
Les explains that this was something never before experienced: God tells the nation of Israel He will give them the Law, the priesthood, and the whole system of sacrificial worship. The purpose was to make them aware of God's holiness and sovereignty, and to prepare them for a future role amid the pagan idolatry all around them. At that time the whole world was steeped in idolatry except the offspring of Abraham. In Exodus chapter 19, as Israel encamped at the base of the mountain and Moses talked with God, God said that if they would obey His voice and keep His covenant, they would be a peculiar treasure unto Him above all people. Les teaches that this lifts Israel out of the mainstream of humanity and puts them into a place of covenant relationship as God's favored, chosen people, just like the lion on the board.