At Sinai the covenant became a truly national covenant. The civil life of Israel was linked up with the covenant in such a say that the two could not be separated. In a large measure Church and Sate became one. To be in the Church was to be in the nation, and vice versa; and to leave the Chuch was to leave the nation. There was no spiritual excommunication; the ban meant cutting off by death.The Sinaitic covenant included a service that contained a positive reminder of the strict demands of the covenant of works. The law was placed very much in the foreground, giving prominence once more to the earlier legal element. But the covenant of Sinai was not a renewal of the covenant of works; in it the law was made subservient to the covenant of grace. This is indicated already in the introduction to the ten commandments, Ex. 20:2; Deut. 5:6, and further in Rom. 3:20; Gal. 3:24. It is true that at Sinai a conditional element was added to the covenant, but it was not the salvation of the Israelite but his theocratic standing in the nation, and the enjoyment of external blessings that was made dependent on the keeping of the law, Deut. 28:1-14. The law served a twofold purpose in connection with the covenant of grace: (1) to increase the consciousness of sin, Rom. 3:20; 4:15; Gal. 3:19; and (2) to be a tutor unto Christ, Gal. 3:24.
—Louis Berkhof, Systematic Theology, 4th edn, 298 (emphasis added).