One major Old Testament racial theme that is inaugurated in Exodus is that of distinction. God's explicit purpose in Exodus is to cause a division among peoples.
"I will make a distinction between my people and your people" (Ex 8:23).
"But the Lord will make a distinction between the livestock of Israel and that of Egypt" (Ex 9:4).
No one could see anyone else or leave his place for three days. Yet all the Israelites had light in the places where they lived (Ex 10:23).
This is yet another huge stumbling block for the educated reader of the Bible, who knows that the one political imperative and moral absolute of our time is "unity." In Exodus, God is practicing overt discrimination. Discrimination is no more than the reverse side of selection. If a man takes a woman for his wife, he selects her above all others and discriminates against all other women he is acquainted with. In fact, he cannot get married without being guilty of "overt discrimination."
In the case of the Egyptians, it was not their race that offended God -- witness Asenath, Ephraim and Manasseh. It was their lack of obedience, their allegiance to gods that defied His purpose. This seems to be the criterion for discrimination in Exodus -- obedience. Did not Moses himself fall subject to God's wrath until his Midian wife circumcised his son (Ex 4:24-26)? What would have happened to an Israelite family that scoffed at the command to put blood on their doorposts? Would not their firstborn have perished along with the Egyptians? There can be no doubt of it.
One final mark of distinction and favor was the despoiling of the Egyptians (Ex 11:2-3, Ex 12:35-36). Israel was not to leave Egypt as a penniless horde of refugees. God adorned them with jewelry and fine clothing, at the expense of Egypt.