Exodus 29:44
And I will sanctify the tabernacle of the congregation, and the altar: I will sanctify also both Aaron and his sons, to minister to me in the priest’s office. And I will sanctify the tabernacle of the congregation, and the altar: I will sanctify also both Aaron and his sons, to minister to me in the priest’s office.
The promise to make holy the meeting tent and the altar, together with Aaron and his sons for priestly ministry, was the means by which God raised Israel from a race of slaves and set them above every other people as His own special treasure. That exaltation was not mere favor but separation from the world for a purpose. In that separation He entrusted them with a sacred trust as keepers and depositaries of His law. That trust was to preserve among mankind the knowledge of Himself.
Through Israel thus sanctified, the light of heaven was to shine out into a world wrapped in darkness. That light was a voice appealing to all peoples to turn away from idol worship to serve the living God. If Israel remained true to the trust, they would become a power in the world. God Himself would be their defense, exalting them above all nations. His light and truth revealed through them would stand as proof of the superiority of His worship over every form of idolatry.