The God of Abraham, Isaac, and Jacob Is the God of the Living
Sadducees pose a resurrection puzzle based on levirate marriage. Jesus replies that resurrection life cannot simply be projected as a continuation of present social arrangements and then argues from the Torah itself: the God of Abraham, Isaac, and Jacob “is not a God of the dead, but of the living.”
Where this fits in the story: resurrection hope is defended from Moses because that is the ground the questioners recognize. Covenant relationship with the patriarchs becomes evidence that death cannot nullify God’s faithfulness.