An idol is anything which displaces God in my heart. It may be something which is quite harmless in itself, yet if it absorbs me, if it be given the first place in my affections and thoughts, it becomes an ‘idol’. It may be my business, a loved one, or my service for Christ. Any one or any thing which comes into competition with the Lord’s ruling me in a practical way, is an ‘idol’.
~ A.W. Pink
Gleanings in Exodus By Arthur W. Pink