IDOLATRY IS THE PRACTICE of ascribing absolute value to things of relative worth. Under certain circumstances, money, patriotism, sexual freedom, moral principles, family loyalty, physical beauty, social or intellectual preeminence, and so on are fine things to have around; but to make them the standard by which all other values are measured, to make them your masters, to look to them to justify your life and save your soul is sheerest folly. They just aren't up to it.
Idolatry is always popular among religious people, but idols made out of things like the denomination, the Bible, the liturgy, the holy images are apt to seem so limited in real power even to their idolaters that there is always the hope that in time they will overthrow themselves.
It is among the unreligious that idolatry is a particular menace. Having ushered God out once and for all through the front door, the unbeliever is under constant temptation to replace God with something spirited in through the service entrance. From the moment the eighteenth-century French revolutionaries set up the goddess of Reason on the high altar of Notre Dame, there wasn't a head in all Paris that was safe.