What is the relationship between Abraham and Moses? We meet Abraham first as Abram way back in Genesis 11 as Abram the son of Terah. Terah and his family were journeying from Ur of the Chaldeans towards Canaan. We meet Moses as an infant in Egypt being cared for and sheltered by his family there. In many ways, these two seem similar as Old Testament leaders, but the other parts of the Bible seem to make a notable difference between them.
Read these New Testament passages about Abraham: John 8:56; Matt 3:9; 22:2; Acts 3:13, 22; 13:26; Romans 4; 9:6; Galatians 3-4; Hebrews 2:16; 6:13-15; 7; 11; Colossians 2:16. The Hebrews passages in particular refer to him living during a period of types and shadows. Is this part of the "old covenant?" Is Abraham a part of that?
In Jeremiah 31:31-34, Jeremiah refers to the "old covenant" as when the Israelites were led out of Egypt. In 2 Corinthians 3:12-15, Paul also refers to Moses as part of the old covenant but not Abraham. In Galatians 3 and 4 particularly, Paul distinguishes between Moses and Abraham. Look in Galatians 3 at Paul saying that the Abrahamic covenant was not changed when the covenant with Moses (Mosaic Covenant) was added more than 400 years later to the covenant with Abraham.
Paul seems to be saying here that the covenant with Moses is old and over but not the one with Abraham. Wasn't God's covenant with Abraham about a promise of land in Canaan? Does this mean that all of these New Testament references to Abraham and God's covenant with him were saying that the Messiah was really just about fulfilling this land promise to Abraham?
Consider what we learn about this from Hebrews 11. New Testament writers refer to Abraham and his promise in spiritual terms not in the earthly terms of Canaan land. Abraham is our spiritual father in the faith. Hebrews here echoes what Jesus said in John 8 that Abraham trusted in Jesus just like us. This is also what Paul wrote about in Romans 4 when he unites we new covenant believers with Abraham who also had faith and believed. So, when we read about the old covenant as obsolete in the New Testament, as in Hebrews 8, we know that these passages are referring to Moses not Abraham.
This raises at least two questions for us. First, if New Testament writers interpret Abraham and his covenant in spiritual terms, even if it was initially also about earthly land in Canaan, how do we spiritually understand Canaan land? Second, if the old covenant with Moses is now over, how do New Testament writers understand its purpose in light of Christ?