“The LORD called to Moses out of the mountain, saying, “Thus you shall say to the house of Jacob, and tell the people of Israel: You yourselves have seen what I did to the Egyptians, and how I bore you on eagles’ wings and brought you to myself. Now therefore, if you will indeed obey my voice and keep my covenant, you shall be my treasured possession among all peoples, because the whole earth is mine. And you shall be to me a kingdom of priests and a holy nation. These are the words that you shall speak to the people of Israel.” (Exodus 19:3-6)
Michael Goheen comments perceptively on the deep meaning of this central Old Testament passage:
“But why would God—the Lord of all nations—liberate this one nation, Israel, and bind it to himself in covenant?…Here [in Exodus 19:3-6] we find the ‘unique identity of the people of God,’ the special role God’s people will play in the rest of the biblical story. In Genesis 12:2-3, God had promised that Abraham would become a great nation to bring blessing to the whole earth; the book of Exodus tells us about that ‘great’ nation formed and called and redeemed to bring that blessing. Specifically, Exodus 19:3-6 tells us how Israel will fulfill its role in delivering God’s blessing…It is hard to overestimate the importance of these words for understanding the role and identity of Israel. As Terrence Fretheim observes, ‘The lens through which one may view the entire Book of Exodus is the speech God utters in 19:3-6. Indeed, it has been said that in the whole tradition of Moses, this is very likely the most programmatic speech we have for Israelite faith’…The rest of the Old Testament offers a narrative account of how well Israel fulfills its calling: ‘This special role [in 19:3-6] becomes a kind of lens through which Israel is viewed throughout the rest of the Bible.’
Three designations describe this special role [given to Israel]: Israel is to be God’s ‘treasured possession,’ ‘priestly kingdom,’ and ‘holy nation.’ The first term, ‘treasured possession,’ refers to a king’s personal treasure. Even though the whole kingdom in some sense belongs to him, the king also has his personal treasure set aside for his own use. Even though God rules over all nations, Israel belongs in a special sense to God and has been chosen for a special task. God’s choice of Israel is put in a universal context: ‘because the whole earth is mine.’ For this reason God chooses Israel: the whole earth belongs to him and he is taking it back. Israel will be the means by which God accomplishes this goal: the renewal of all creation and all nations. As Williamson notes, ‘Israel’s election as Yahweh’s ‘special treasure’ is not an end in itself, but a means to a much greater end. Thus understood, the goal of the Sinaitic covenant is the establishment of a special nation through whom Yahweh can make himself known to all the families of the earth.’ How Israel will play this role is set forth in two images: it is to be a priestly kingdom and a holy nation…
What priests are for a people, Israel as a people is for the world. It is instructive here to consider three elements of the role of priest in the Old Testament: he is to be set apart in holiness, to mediate God’s presence and blessing, all for the sake of others. A priest is set apart and devoted fully to the Lord: this is the very essence of what he is to be and to do. He is to function as a mediator and channel of God’s holy presence to the community through his own holy life and behavior, a model of consecration and devotion to God…Israel is likewise called by God to mediate his presence to the surrounding nations, to be a tangible evidence of his living reality in its midst. All of this the priest carries out for the sake of others. The priest’s life is not for himself: he lives to bring blessing to Israel. God commands Aaron and his sons to bless the Israelites: ‘The Lord bless you and keep you; the Lord make his face shine on you and be gracious to you; the Lord turn his face toward you and give you peace’ (Num. 6:22-26). Likewise, God had promised that the nation to come from Abraham would bring blessing to all other nations; in this way too Israel is to fulfill a priestly function before its neighbors. Dumbrell can even say that the call of Exodus 19:4-5 is a ‘virtual restatement of Genesis 12:1-3.’…
The other title, ‘holy nation,’ expresses a similar understanding of the people’s identity and role. Holiness is the special quality of something that has been withdrawn from normal use and consecrated to God’s service. As a holy nation Israel is to withdraw, as it were, from the nations. The lives of Israel’s people are to be markedly different from those of the peoples around them. As Durham notes, they ‘are to be a people set apart, different from all other people by what they are and are becoming—a display people, a showcase to the world of how being in covenant with Yahweh changes a people.’ As a holy nation they are to live as a model or paradigm before the world of what God intends for all…Israel is to embody God’s creational intention for all humanity for the sake of the world, living in such a way as to draw the nations into covenant with God. Or, to use the later language of Isaiah, Israel is called to be a ‘light to the nations’ (Isa. 42:6).
Thus Israel’s calling from God to be a priestly people and a holy nation sets the people explicitly in the middle position between God and the nations. On the one hand, they are set apart for God’s glory and purpose, oriented toward him to make known his majesty and thus play their role in his mission; on the other hand, they are set apart for the sake of the nations, oriented toward the surrounding peoples to be to them a mediator of God’s blessing. The covenant set before Israel in Exodus 19:3-6 gives it this missional role and identity amid all nations. Moses summons the elders to respond to God’s call, and they affirm, on behalf of all the people, ‘We will do everything the Lord has said’ (Exod. 19:8).” (Michael Goheen, A Light to the Nations: The Missional Church and the Biblical Story, pp. 37-40)