Im pretty sure that most foods that are forbidden in different religions, have become such because the people in past times didn't necessarily know how to cook them right and so if someone became sick, and people didn't have the knowledge of existence of bacteria and parasites, they became forbidden.
For example pig meat: pigs are known to carry Trichinella spiralis and that you have to cook them well before the eggs of this parasite die.
The people didn't know this in the past, and because some people actually then ate not fully cooked meat, got sick and died, it was tought that god didn't want people to eat pigs.
Same with shellfish, some of them are actually poisonous no matter if you cook them and use only fresh, living ones, I doubt that people knew that you can't eat the already dead ones, those that have opened their shell before cooking.
The list goes on and on, there is no animal that I can think of that is accepted food in all cultures and religions.
The point is, that know in modern times when we actually know what causes deceases through food, be it for contamination or some other reason, I think its really dumb to still grasp on these rules.
The jews and muslims can see that some people eat pigs and get on their lives just fine, same with shellfish.
Same is with eating insects which is considered taboo in many cultures, we can clearly see that some people eat them and are just fine.
These days when we are living in overpopulated world I think these taboos should be broken to be able to feed people with local ingredients as much as possible.. of course many religious people will think that famine is the will of god, or is it?
Hopefully someday people will open their eyes and use their heads for themselves..