[one Lord one faith one baptism]

there had to be a new covenant, since the old covenant was FULFILLED.
Jesus Christ fulfilled the old covenant and this qualified him to be the mediator of the New Covenant, a Covenant sealed by the shedding of His blood for the remission of sins.

[editor-surveyor]

No, actually the covenant will be fulfilled when all of Yehova’s elect are in the New Jerusalem, and that is also a good demonstration that it is truly a renewal of a covenant with a people that had become “not my people” at one time, but now are again his people. (Hosea, 1Peter)
.