Exodus begins with the fulfillment of the creative work of God declared Genesis: 

…The Israelites were fruitful and prolific; they multiplied and grew exceedingly strong, so that the land was filled with them. Gen. 1:7 

As Genesis ends, God has provided for the Israelites through Joseph, the last of the patriarchs. With his death begins a new chapter in the story of God’s covenant: the liberation of the Hebrews from the power of death embodied by an evil King:

Now a new king arose over Egypt, who did not know Joseph.  He said to his people, “Look, the Israelite people are more numerous and more powerful than we.  Come, let us deal shrewdly with them, or they will increase and, in the event of war, join with our enemies and fight against us and escape from the land.” Gen. 1:8-10. 

While the story of the Patriarchs of Genesis—Abraham, Isaac, Jacob—is a “sharply etched story of individuals” (Alter 299), Exodus tells the story of a people. The God of Genesis who engages with humans, is easily mistaken for a human until he reveals his identity, in Exodus becomes unseeable, speaks without becoming visible, and is represented by fire. While Abraham sees God and talks face-to-face, Moses cannot look at God, lest he die (Alter 301).

The change in the ways God is revealed in Exodus has to do with the fulfillment of the covenant with Abraham, the movement of the story of God relating to individuals to the God of a people. In this sense, God’s power is revealed in history on a grand scale:

God in Exodus has become more of an ungraspable mystery than he seems in Genesis, as he moves from the sphere of the clan that is the context of the Patriarchal tales to the arena of history.  His sheer power as a supreme deity as implacability against those who would threaten his purpose emerge as the most salient aspects of the divine character.  Alter 302

Brueggemann says the core theme of Exodus is covenantal liberation:

What happens in [Exodus] thus serves to make abused, oppressed persons subjects of their own history, able and authorized to take responsibility for their own future. 683

This central theme is written in socio-economic, and political terms.

The teaming masses Pharaoh fears migrated to Egypt during the famine to be fed on the grain of Joseph’s storehouses. In exchange for food, these migrants were put to work making bricks, building Egyptian buildings. They are not the literal descendants of Jacob / Israel; they are called Israelites because they are the offspring of Joseph’s provisioning. These people are diverse among themselves, migrating from the lands around Egypt, but they look the same to the people who enslave them:

They are named “Hebrews,” referring to a category of people who “have no social-standing, no land, and who endlessly disrupt ordered society.  They are low-class folks who are feared, excluded, and despised.” Brueggemann 695 

The term “Hebrew” is rendered from the original apiru, a term denoting not a religion or a religious community, but no-count people who have nothing and are socio-economic burden and threat to the established order.

The story of Exodus is of God’s mighty power to create a nation by librating these people from the power of death, giving them a law to live by, establishing a covenant with them, and being present with them on their journey through the wilderness to the promised land.

Exodus is a story of creation—creation through liberation, law, covenant, presence—organized around the theme of water. Egypt, on the Nile, is associated with water, and water will figure in Pharaoh’s demise. When the Hebrews are delivered, they set out into the Sinai wilderness, a land of parched dryness.

The story begins with the King of Egypt’s genocidal plans eventuating with Moses afloat on an ark into the reeds, drawn up out of the water at the behest of Pharaoh’s own daughter, who later takes him (adopts him) as her own, and raises Moses as a prince in Pharaoh’s own house.

Resources
Alter, Robert. The Five Books of Moses. New York: Norton & Company. 2004.
Brueggemann, Walter. New International Bible. Vol. I. Nashville: Abingdon. 1994.
Charles B. Cousar, et al. Texts for Preaching. Louisville: Westminster John Knox P. 1995.