Questions always arise as to whether the use of Catholic Symbols is really a form of idolatry. Usually it is because the questioner isn't altogether acquainted with what these symbols actually are. We do not worship the crucifix. We use it remember of Jesus suffering and death for the sins. We don't worship the fish. We display it as being a proud emblem in our Christianity. We don't worship the statues of the saints. We rely on them to point out their wonderful lives so that they might be role-models for all of us to emulate.
As far back as when the Ten Commandments received to Moses, idolatry within the Old Testament was understood to be the worship of idols or images. It is the worship of not God that is wrong and sinful. The mere images, symbols or icons are not the problem.
An excellent example of this within the time of Moses may be the Brass Serpent. God commanded Moses to create this Brass Serpent and lift it high for stopping any Israelite who looked at it of snakebites. I repeat it was God who commanded Moses to create this picture. Later ever, King Hezekiah destroyed the Serpent since the Hebrew people had been burning incense to it in worship. The symbol had eventually be an object of idolatry. Begin to see the difference?
When God gave commandments regarding idolatry he meant so that it is understood in its most literal form. Based on the Bible, most idolaters really believed that their idols were gods. That isn't so today with Catholic Symbols.