Did Abraham come from an idolatrous background?
Yes. Scripture shows Abraham's forefathers, including Terah his father, dwelt beyond the river and served other gods; they were idolaters. God called Abraham out of that idolatrous civilization, taking one man from an idolatrous background to begin the nation of Israel.
Les explains that God called one man, Abraham, out of idolatry, and points to Joshua 24:2. There Joshua tells Israel that their forefathers, including Terah, Abraham's father, and Nahor, dwelt on the other side of the river and served other gods. They were all idolaters. Out of that idolatrous civilization, God took one man, Abraham, and that became the beginning of the nation of Israel, commonly called the Jew.
And Joshua said unto all the people, Thus saith the LORD God of Israel, Your fathers dwelt on the other side of the flood in old time, even Terah, the father of Abraham, and the father of Nachor: and they served other gods.