In Exodus 19, the people of Israel have been brought to Sinai, the mountain of God. They have already been rescued from the death and slavery of Egypt. Now, after they have seen the great salvation of God in the overthrow of their enemies, they are being prepared to receive the law. God tells them that if they will obey His voice and keep His covenant, they will be His treasured possession, a kingdom of priests and a holy nation.
The words obey and keep here are a sort of summary of the priestly duties of this kingdom of priests. Obey is shema’ in Hebrew, the same word translated hear in Deuteronomy 6, “Hear, O Israel, Yahweh our God, Yahweh is one.” To truly hear the voice of God is to obey. To hear without obeying, James says, is self-deception. It is idolatry, looking at yourself in a mirror and seeing there only what you would expect. Hearing with obeying reveals and transforms, and the one who obeys is blessed in his doing. Israel was entrusted with the oracles of God to hold up as a mirror to themselves and to the greater Gentile world. They were to hear and obey so they could teach the surrounding nations to do the same, transforming the world and guiding them in right worship of Yahweh.
Likewise, the word keep is tied up with the duties of the priests and Levites in the tabernacle and the temple and goes all the way back to Adam’s duty in the garden sanctuary. Along with observing and celebrating the covenant, it carries the idea of watching, guarding, protecting, and preserving. The nation acts as guardian cherubim, guarding the way to the tree of life with the flame and sword. This was not to keep everyone away, but to ensure that those who approached did so rightly. They were to keep the covenant pure, to keep it from being mishandled or compromised through intermingling with false worship.
In obeying and keeping covenant, they were being transformed into a holy nation, remade in the image and likeness of the glory of God. They were invested with this glory image in a physical way in the construction of the tabernacle and the priests’ robes which reflected the presence of the glory cloud hovering over the Most Holy place. In a similar way, Peter says we are being built into a house of living stones, a dwelling place of the Spirit. We, the church, are a chosen race, a royal priesthood, a holy nation, a people for God’s own possession so that we may proclaim the excellencies of Him who called us out of darkness into His marvelous light, the light of the image of His glory, the light that shone into the creation to bring it into the fullness of the glory and pattern of heaven.
Because we are called into the light of His kingdom, we are to live like people of the light. Our lives are to reflect the glory of God by being holy as He is holy. Our lives are to be lives of hearing and doing, of keeping covenant so that we live holy and blameless before Him.