How did God initiate His relationship with Abram out of a pagan world?
God initiated the relationship by appearing to Abram and speaking to him directly, telling him to leave his country, kindred, and father's house. Because Abram's family were idolaters and pagans with no knowledge of the one true God, God singled him out from a pagan world and directed him to a land He would show him.
Les explains that God began with Abram in Genesis 12. The Lord had said unto Abram, “Get thee out of thy country, from thy kindred, and from thy father's house,” because Abram's family were idolaters, idol worshipers, and pagans who had no knowledge of the one true God. Out of the whole then-known world saturated with pagan worship, God put the finger on one man, appeared to him, spoke to him, and told him to leave his idolatrous family, make the break from paganism, and go to a land God would show him. Les also notes Abram was not totally obedient; he puts the blame on Abram's father, since the father said they would go with him. God stopped him halfway between Ur and Canaan until Oterah died.