The prohibition on idols is the second commandment to Jews and most Christians, but still part of the first commandment for Catholics. If I may play child-molester’s advocate, I can see why Augustine combined these three sections (I am your god, no gods before me, no idols) into a single commandment—they all pertain to the same thing: monotheism. Is there really a big difference between worshiping a different god and worshiping an idol of that god, especially when people of this time didn’t really differentiate between an idol and what the idol represents?
In fact, when you read all of Exodus 20:1-6, it really seems like the whole thing fits together as one. There is a preamble, prohibition, and a closing explanation. In this case, I think the Catholics have it right.
Of course, most believers don’t look too carefully at this commandment, and for good reason. Sure, they’ll see the part which tells them not to make any graven images, and they may even come up with a weak excuse about how God can call himself jealous and still be perfect, but they always dance around the part where God says he will punish four generations of people if they dare disobey this commandment because they realize the severe immorality of it! You’ll find monuments to the Ten Commandments all over the place, but they wisely excise this part. Want a fun way to really anger the Lord? Worship an idol, but never have kids! Oooo, he’ll be so pissed that he can’t torture your great-grandchildren!
Interestingly, God’s clarification that you can’t make idols of anything in the sky, on the Earth, or in the water doesn’t exclude idols of imaginary creatures (like gods, angels, demons, unicorns, chupacabras, etc.), since none of these things live on Earth! Of course, I, like most people, interpret this to be a merism. In the same way, if you’re told to search someone “head to toe,” it doesn’t mean you can should the arms because they’re not on a direct path between the head and toes.
Finally, God ends by saying that those who keep his commandments will be shown mercy and receive love, which implies that who don’t keep his commandments will not be given mercy or love. So much for a forgiving god.
I have broken this commandment in the sense that I think a pair of worn-out socks is better than God.