I’ll have to be brief here, because you either need a book or two about Abraham and God’s covenant with him, or you need a very brief synopsis. So, since there is no time, I will sum up:
1. We have no reason, Scripturally, to believe there was anything about Abram that caused God to call him. In fact, if Deuteronomy 26:5 (and surrounding) is any indication, the Israelites were to remember well that there was not much about their ancestry to boast in.
There are scribal and Hebrew traditions that suggest great things about Abraham, including a story that claims his father was an idol-maker by trade and Abram came to believe in monotheism. So, one night, Abram smashed his father’s shop full of idols and left just one standing, putting the hammer beside it. The next day, Terah asked who had done the damage and Abram pointed at the remaining idol and blamed it. Terah said it was impossible, it’s just a statue. Abram said…Why worship it?
It’s a great story. It’s not in Scripture and so, as people of the Word of God, we can accept it or reject it. Given the general lateness of it—written many centuries after Moses—I tend to think it’s a bit like some of the Parson Weems’ tales of George Washington, intended to spur amazement at our ancestors.
Instead, the call of Abram is the call of God’s grace.
2. There’s much to be seen here about how God immediately brings about the promises of Genesis 12:1-3. Pharaoh is a threat, and God responds. Lot is a threat, and God moves him on…and so forth. God also will continue to work in fulfilling that promise, though I think the greatest fulfillment of Genesis 12:3 is through Jesus. There is no greater blessing for all the peoples of the earth than salvation!
And, yes, “peoples” is the right word. The idea here is that God’s grace is not just for a few, not just for those who can trace their birth back to Abram. But instead, it is glad tidings of great joy which is for all the peoples—unto us is born this day, the Savior, Christ the Lord! (What, you think Luke didn’t know Genesis?)
3. You see in the rest of the narrative issues of trust. Abram is afraid of Pharaoh and lies, risking his wife in place of his life. In 13, he and Lot quarrel. Over time, we see Abram forced to choose to trust God above all others: there is no nation for him, no natural heir for him, no home.
Except the home God will bring him.