Jesus held that God’s describing himself to Moses as Abraham’s God, Jacob’s God, and Isaac’s God referred not merely to a part relationship which no longer existed. By his very nature God is the God not of the dead but of the living. In calling these patriarchs into covenant with Himself, He had established a relationship with them that was not terminated with physical death…’Death is a change of relation to the world and to men, it does not change our relation to God.’
D. Edmond Hiebert
Commenting on Mark 12:26-27