The Masked One wrote:general kindness = let them use my coal to smelt, not take it.
Taking it and using it to smelt is pretty much the same thing, you know. And how would you know if they took it out or used them anyway? Your logic is terrible right now. If you want them to use the coal in your furnace, and they used it, then there wouldn't be coal left in it. You're saying that you think that they took it out for a different purpose, and that's why there is no coal in your completely out in the open furnaces. How would you know? And even still, the only other use that coal has is to power minecarts and craft torches, which are, frankly, not that big a deal. I have no idea why you're complaining about coal, let alone assuming someone stole it when there is an equally high enough chance that someone used it to smelt as intended.
Now, something like your inventory being taken by a warzone, I understand. But your stuff is your responsibility, and whether or not you choose to lock your stuff is completely out of my control. I'm willing to compromise on certain occasions, but coal is one of the easiest resources to gather. You don't even have to mine to get coal anymore.