A good definition of "idol" is any thing that takes the place of God in our thinking. We talk about people whose idols are their cars, or success, or house...things.
We all need money. We need it to buy food, or have a place to live. When does money become an idol ? When we cease to think of it as a thing: when we invest it with a spiritual quality against God's place in our spirit: love, for example, or trust. If we ascribe the qualities of a living relation to what is only a thing, we create an idol in our life.
