Was the covenant promise given to Abraham spiritual or earthly in nature?
The covenant promise given to Abraham was spiritual, not earthly. It was heavenly in origin, never left the hands of spiritual beings, and Abraham became only its subject. Though his offspring repeatedly broke it, God kept it settled and will not go back on it.
Les explains that this whole covenant promise made to Abraham was spiritual and never left the hands of spiritual beings; it was heavenly in origin. Abraham became the subject of it but could not touch or change it. Even though his offspring would break it again and again, God kept it settled and will never go back on it. That is why God is not through with Israel and will still finish and fulfill those covenant promises. Les further notes that God alone is mediator, instigator, and fulfiller, so the covenant does not depend on a three-person mediation.