When Abraham was called, he was literally living in Babylon on the plain of Shinar in the city of Ur. He did not come from a God-fearing family, and there is no evidence that he was converted at the time of Genesis 12:1. Every indication is that he, too, was a heathen. As we shall see, every called person begins in idolatry.
God had in all likelihood begun to work with him, preparing him for his calling by guiding his thinking to begin to question areas of life he had previously accepted without question. Historical traditions indicate that his family was of a priestly caste, and perhaps he was already questioning the validity of the false gods he served.
Acts 7:2-4 clarifies a few things relating to the early period of his calling:
And [Stephen] said, "Brethren and fathers, listen: The God of glory appeared to our father Abraham when he was in Mesopotamia, before he dwelt in Haran, and said to him, 'Get out of your country and from your relatives, and come to a land that I will show you.' Then he came out of the land of the Chaldeans and dwelt in Haran. And from there, when his father was dead, He moved him to this land in which you now dwell."
What is included in God's appearance is not known. Whether it was literal, in a vision, or by dream is not explained anywhere else. The element we need to understand is that, as with us, Abraham did not earn his calling. He had done nothing to earn or deserve God's notice.
Isaiah 51:2 adds a further piece of information worth considering: "Look to Abraham your father, and to Sarah who bore you; for I called him alone, and blessed him and increased him." While Sarah is at least mentioned, no other family members are included within the scope of this statement. It appears that several members of Abraham's family depended on him, since much of his family left with him, yet God makes clear that Abraham was the only one spiritually called.
To how many of us has a similar thing happened? Why does this happen? Nobody knows! It is unanswerable. God shows mercy to whom He shows mercy. He loves Jacob but loves Esau less by comparison, despite their being twins. He accepts Abel and rejects Cain. He chooses only Noah among millions of others to whom He could have given grace.
This we know: At some time before leaving Babylon, God became a living reality to Abraham to a degree no one else near and dear to him experienced. Even amidst his personal self-seeking and self-pleasing, he was motivated to leave his set routines of life. It must have been similar to what Job experienced when he said, "I have heard of You by the hearing of the ear, but now my eye sees You" (Job 42:5).
Whether the opening of Abraham's mind was gradual or sudden, God had graciously revealed Himself enough to make him move, and he did so to the extent of leaving his homeland and journeying over 1,200 miles, probably on foot or at best by donkey or cart, to a land known for violent weather, especially for its high temperatures.
Abraham was already 70 years old, yet he severed virtually every relationship that matters to normal human concepts of life and well-being. For a long time, stability became a thing of the past, considering that he never again dwelt in a home with foundations. This may seem an unusually hard and harsh requirement. Nevertheless, he embarked on a journey into an utterly unknown future.
What can we learn from this God-engineered example? Undoubtedly, He was testing Abraham, a process we should expect a measure of in our calling as well. We may never have to leave our homeland and set out on a long journey without knowing where we are headed, but it is highly likely that disruptions will accompany our calling.
A primary instruction God wants us to understand from Abraham's calling is that we must make a complete break from our old lives. We must clearly begin to sever ourselves from the old, "inner" life that was implanted in our character by our living according to the course of this world (Ephesians 2:2).