I recently came across a comment by a person named Teresita who stated that she was "raised Catholic" and who seems to think that "veneration of some people's bones has a biblical basis, so the Catholic practice can't truly be called idolatry." (source)
Teresita went on to quote Exodus 13:18-19, which I'll reproduce below:
18But God led the people about, through the way of the wilderness of the Red sea: and the children of Israel went up harnessed out of the land of Egypt. 19And Moses took the bones of Joseph with him: for he had straitly sworn the children of Israel, saying, God will surely visit you; and ye shall carry up my bones away hence with you.
I don't really see how the fact that Moses took the bones of Joseph with him is supposed to be analogous at all to the superstitious and (in some cases) idolatrous practices associated with relics. After all, in essence the pilgrimage from Egypt to Israel included a hearse, in which the box of bones of Joseph were carried. It's tough even to guess what the similarity is supposed to be. Is the idea that there was some sort of reverential treatment of Joseph's corpse? If so, ok ... but that's not all that the objectionable papist practices entail.
Perhaps they imagine that Joseph's bones were paraded about and put on display or that prayers were offered to Joseph (though there is not the least shred of Biblical evidence for such a thing). Let me provide the evidence for both why they did what they did and the full picture of what they did.
Why they did what they did.
24And Joseph said unto his brethren, I die: and God will surely visit you, and bring you out of this land unto the land which he sware to Abraham, to Isaac, and to Jacob. 25And Joseph took an oath of the children of Israel, saying, God will surely visit you, and ye shall carry up my bones from hence. 26So Joseph died, being an hundred and ten years old: and they embalmed him, and he was put in a coffin in Egypt.
You see, Joseph (who was a prophet) made the people of Israel swear (to the still-living Joseph) that they would bury him in the promise land. So, when he died, they embalmed him, placed his body in a coffin, and stored it.
Many years past. Eventually, as Joseph prophesied, the people went up out of Egypt. Although the Pharaoh had forgotten about Joseph, Moses and the people of Israel had not forgotten. They fulfilled their promise (as shown in Exodus above) and carried his bones out of Egypt and into the wilderness.
Finally, the arrived in the promised land:
Joshua 24:32 And the bones of Joseph, which the children of Israel brought up out of Egypt, buried they in Shechem, in a parcel of ground which Jacob bought of the sons of Hamor the father of Shechem for an hundred pieces of silver: and it became the inheritance of the children of Joseph.
What did they do? They did what they promised, they buried his body. They did not put it on display for various acts of necromancy. In fact, there's no indication that they ever took it out of its coffin. Recall that to touch a dead body was ceremonially unclean under the law of Moses, and consequently there would have been good reason to simply leave the bones in their coffin and bury the bones coffin and all in Shechem at the end of their long, prophesied, and promised journey.
The papists also sometimes bury the bones of those they think are particularly holy. Then, later, they exhume those bodies and put them on display. That's really not at all analogous to what happened here. In fact, the only particularly surprising here is that the bones were not more or less immediately buried. There was, however, a particular reason for that non-burial: a promise made to the living (not communication with the dead).
In short, on the basis of exegetical analysis of the text, we can reasonably reject the idea that it provides even the least shred of support for the practices of the Romanist church with respect to dead bodies and parts of dead bodies.