Was Abraham an idolater before God called him?

Yes. Abraham was steeped in idolatry as a young man in the city of Ur before God called him. God reached down in grace, told him to leave the city and family, and go to a place God would show him, and Abraham believed God.

Les explains that Abraham was steeped in idolatry as a young man in the city of Ur. God reached down in grace and told him to leave the city, leave his family, and go to a place He would show him, and Abraham believed God. Paul later builds his case that Abraham was declared righteous only because he believed God, not because of works.

Was Abraham steeped in idolatry while he lived in Ur?

Yes, Abraham was steeped in idolatry as a young man while living in the city of Ur. God reached down in grace and told him to leave the city and his family, and Abraham believed God, which was accounted to him as righteousness.