The last catechism answer showed us that sin is rejecting, ignoring, and rebelling against God, not treating God as God, and not giving him the honor that is his due. In the Bible, the most frequently described way that human beings do that is through the sin of idolatry. Idolatry is loving anything more than Jesus Christ. Idolatry is treating anything as more important than Jesus Christ for your meaning in life, for your happiness, for your security and hope, or for your self-regard. The reason why it’s so important to understand the sin of idolatry is that it can be growing in a part of your life for a long time and get very deep without it right away leading to clear, visible, and easily seen violations of God’s law.
So, for example, if affluence and your career have become too important to you, they’ve become idols, and that can lead you to working too hard and exhaustion. It can lead you to becoming ruthless. It can block the development of a loving heart and the fruit of the Spirit. It can thin out your relationships. It can hurt your family relationships. It can hurt your friendships. And all these things can be going on for a long time before it leads to a real overt example of lying or cheating or adultery, because idolatry can lead to those things.
So what’s important to grasp is this: sin is not just doing bad things. It’s turning good things into ultimate things, because it ruins your soul, destroys community, and dishonors God.
What is it to have a god? Or, what is one’s god? Answer: To whatever we look for any good thing and for refuge in every need, that is what is meant by “god.” . . . Many a person imagines that he has God and everything he needs, provided he has money and property. . . . The evidence for this appears when people are arrogant, secure, and proud because of such possessions, but desperate when they lack them or lose them. I repeat, to have a god means to have something on which one’s heart depends entirely.
Question and explore your own heart thoroughly, and you will find out if it embraces God alone or not. Do you have it in your heart to expect nothing but good things from God, especially when you are in trouble and in need? And does your heart in addition give up and forsake everything that is not God? Then you have the one true God. On the other hand, is your heart attached to and does it rely on something else, from which you hope to receive more good and more help than from God? And when things go wrong, do you, instead of fleeing to Him, flee from Him? Then you have another god, a false god, an idol.