The term IDOL, in its original sense, is the name for those false gods, to which human blindness and unbelief have given an outward form, and have set up and worshiped instead of the true God. In its secondary or figurative sense, it is the appropriate name of any object or person, which attracts and concentrates upon itself any affection, or any degree of affection, which belongs to God.
It is worthy of notice, that the ennobling principle of love is the basis of idolatry, as well as the basis of true holiness. But holy love, or love in the true sense of the terms, is always right. Idolatrous love is always wrong love; — wrong either in its place or its degree. And if right love is the highest and best exercise of the heart, it is difficult, on the other hand, to estimate the evil results of a love that is wrongly placed.
Objects, which may easily become idols, by being the subjects of an affection which is wrongly placed, surround us on every side. They are sometimes said to be innumerable. And if that be too strong an expression, it is certain that they are limited in number only by the capacity of inordinate love. This beautiful world, beautiful even in its ruins. which was originally designed to be the temple of God and of his worship, has become one great idol temple. A man's idol may be his property, his reputation, his influence, his friends, his children, those who are bound to him by the ties of natural affection, and even those who are united by religious attachments, and all other persons or things which are capable of being objects of affection, and which can attract that affection in an inordinate degree.
— A Treatise on Divine Union (1851) Part 4, Chapter 9.