Well for starters, let's see how he DID or DIDN'T respond to God when called to leave his homeland and go to a place that God would show him. Let's put ourselves in his sandals and see what WE would have done.
(This is a section from the Catholic Scripture Studies guide I am writing on Genesis.)
"Now the Lord said to Abram, ‘Go from your country and your kindred and your father’s house to the land that I will show you. And I will make of you a great nation, and I will bless you, and make your name great, so that you will be a blessing. I will bless those who bless you, and him who curses you I will curse; and by you all the families of the earth shall bless themselves.’” (Genesis 12:1-3).
That is all that Abram had to go on. We are not aware of other conversations or proofs that God may have given to Abram—just pack up and go to — well, he didn't know where to!
So, put yourself in Abram's sandals:
“Where Lord; where do you want me to go?” you ask. God says, “I already told you—to a land that I will show you.” “But Lord,” you answer, “I have a house and cars, a job and a family here.” “I’ve noticed,” replies God, “sell everything you can’t transport to another land, and pack the rest. Then I will tell you where to go.” “Where is this land you want us to to?” “I haven’t told you yet,” God says, “ just get packing.” “But God, if I quit my job here, will I have work in this new place?” “Don’t worry” answers God.
Under your breath you mutter, “Don’t worry?” Then you turn back to the Voice and say “What about a house and everything else we will need? What about a mortgage and an employment contract?” Patiently God responds, “I haven’t promised you any of that right now,” says God, “just trust me; I will bless you.” You turn away and mutter again, “Trust him?” before turning back to the Voice, “What do you mean trust you? What do you mean that will bless me? I have family here and no sons to care for me in my old age. I am already seventy-five years old—I’m past retirement and you say ‘Trust me?’” “Yes,” says God, “trust me to bless you!” “Hey God, where did you say we are going again?” I didn’t say, but I will show you.”
You are still thinking about all this and ask, “Should I leave my other gods here, all the idols we have worshiped for generations?” Now God mutters under his breath, “Who does he think I am?” Then with a bit of exasperation God exclaims, “Of course you should get rid of the idols; from now on I will be your God.” “But,” you answer, “I don’t even know your name.” “My name is not important right now, just do as I tell you” says God. You hesitate for a few minutes, scratching your head, then you ask “Are you sure I can trust you? And where did you say we are going again?”
That’s how most of us would have responded to God—part of the reason we are not the “father of the faith.” Abraham was no fool. He wasn’t gullible or easily pushed around (his actions displayed throughout his life prove that). He was not stupid, but neither was he set in his ways and stubborn. He was a bright man who was smart enough and decisive enough to perceive the truth. He put his life, his family, his possessions and his whole future in the hands of God—and God would not let him down.
"So Abram went, as the Lord had told him; and Lot went with him. Abram was seventy-five years old when he departed from Haran. And Abram took Sarai his wife, and Lot his brother’s son, and all their possessions which they had gathered, and the persons that they had gotten in Haran; and they set forth to go to the land of Canaan. When they had come to the land of Canaan," (Genesis 12:4-5).
“And without faith it is impossible to please him. For whoever would draw near to God must believe that he exists and that he rewards those who seek him. . . . By faith Abraham obeyed when he was called to go out to a place which he was to receive as an inheritance; and he went out, not knowing where he was to go” (Hebrews 11:6, 8).