NOTES for Gen 12:4
What could a historian tell us about Abraham's migration? He could tell us, perhaps, that in the age of the Patriarchs many Semitic tribes migrated west, settling across the broad dry steppe that stretched from the western borders of Mesopotamia to the eastern coast of the Mediterranean Sea. That Abraham certainly was not the first chief to lead his kinsmen into Palestine. That in antiquity many people heard the voices of gods and spirits, and not so rarely, and they listened to those voices. That, of course, when a person was already past seventy, it was still rather late to begin a new life and set out on a not very long but very dangerous journey; one could decide on such a thing only under special circumstances.
But no historian will tell us about the most important thing, because historical sources are silent about that most important thing. And that is no surprise: the most important thing is hidden deep in Abraham's heart. Having heard the voice of the God still unknown to him, he believed and went where this unknown God called him. He went fully understanding that no one guaranteed him anything: he still had to come to know the One who called him more closely in order to understand with whom he was dealing. And here everything depended only on Abraham's own choice. God does not force him to do anything; He only calls him to follow. Could Abraham have said "no" to God? Yes, of course; a human being is free. But then, when we said "the people of God," we would mean another people with another history.