Gal 3:20

3:20 intermediary. Moses mediated between God and Israel when God made His covenant with Israel at Mount Sinai (Ex. 19–34). The promise given to Abraham, however, required no mediator and therefore takes precedence over the covenant at Sinai.

God is one. See Deut. 6:4. God’s covenant with Abraham, because it did not involve a mediator, demonstrated God’s unity and sovereignty more perfectly than the covenant at Sinai. The fulfillment of God’s covenant with Abraham by the inclusion of the Gentiles in the people of God also demonstrates the unity of God more clearly than the Sinai covenant because it shows His sovereignty over all creation (Rom. 3:29, 30).