Abraham is instructed by God to do what we humans fear most, to be uprooted, to leave home and hearth for an unfamiliar destination. The midrash feels the depth of his anxiety. God needs to reassure Abraham that he will not end up alone and destitute. The divine command casts Abraham in the role of outsider. He repudiates what has grown conventional, comfortable, and constricted.
Monotheism challenges the fundamental tenets of Mesopotamian civilization.
Abraham anticipates the fate of his progeny as eternal aliens, the vigilant critics of the societies in which they temporarily reside. To serve as a blessing for all nations means to see things independently and different from the margins of the body politic. The midrash suggests that Abraham was actually expelled from his homeland. The command to leave did not come unannounced. He had long struggled to formulate a conception of God more in tune with reason, ethics, and existence than offered by the myths of paganism.