ISB ~ Galatians 3 v20

an intermediary:Moses, who delivered the Torah to Israel (Ex 20:18-22; Deut 5:4-5). That the Mosaic covenant involved a mediator implied that more than one party was responsible for fulfilling the terms of the covenant—God and Israel. The Abrahamic covenant, by contrast, was a unilateral arrangement, i.e., God alone swore an oath and assumed the responsibility of blessing the world through Abraham’s offspring (Gen 22:16-18).

God is one:The monotheistic creed of ancient Israel (Deut 6:4).