Atheist here, just reading this thread out of curiosity. The very idea of a physical religious symbol having some sort of intrinsic property that demands respect I find rather odd. I mean, I can understand respect for a religion, and to that end I certainly would understand why you would not deface such an object in front of followers of said religion, just as you would not burn the flag of a nation in front of its citizens. Once in private, though, the object would seem to be nothing more than a formed piece of metal, wood or what have you, and in that case, why would you not treat it as scrap as you would if it was something else? At some point, someone (or possibly some automated machinery) made the symbol from raw materials with no such value. At what point did it become deservent of such respect in disposal?
Perhaps, out of respect for the environment, I could understand recycling it, but that’s about it.