The heart may be turned away from God in many ways. How subtle are the workings of evil; how hidden are it motives; and therefore its influence is extensive. According to John Angell James:
The apostle John closes his first epistle with the following tender and solemn admonition —”Little children, keep yourselves from idols!” Those to whom he thus addressed himself had been converted from Paganism, and needed to be cautioned against relapsing into their former idolatry, and against every practice, which would in the smallest degree seem to countenance it. There is no need that I should warn you against this sin in its literal import. You have never bowed the knee to a graven or molten image, and never will — but is there no such thing as SPIRITUAL idolatry? The first commandment of the Decalogue says —”You shall have no other gods before me.” The meaning of this precept, which is the foundation of all religion, is not merely that we shall not acknowledge any other God besides Jehovah — but also that we shall treat him as God! That is, we must love him with all our hearts, serve him with all our lives, and depend upon him for our supreme felicity. It is obvious that all this, as well as prayer and praise, is the worship that God requires.
The bended knee, whether this be done to God or an idol, is of no value—but as the expression of the state of the mind and heart at the time. The affections are a much more sincere and expressive homage than bodily attitudes and outward forms of devotion. Hence, it is obvious that — whatever we love most, and are most anxious to retain and please — whatever it be we depend most upon for happiness and help — whatever has most of our hearts — that is, in effect, is our God! — whether it be Jehovah or Jupiter, or whether it be friends, possessions, or our own desires, or our own selves! Is it not, therefore, to be feared that the hearts of many professors are going too much after other objects of worship than God, and need the admonition, “Little children, keep yourselves from idols!” (“Spiritual Idolatry”)