[Gayle]

There's usually a reason for religious beliefs to be 'adopted'. For example, and I was told this by a muslim before anyone has a go at me, pigs have no necks therefore unable to be cut by the halal method, things that can't be killed in that way are therefore not killed correctly. Also, the countries where the muslim faith originates are extremely hot - pigs, because they have no necks are less able to regulate their temperatures and so are therefore more likely to be diseased and finally, pork does not keep for very long in the heat therefore can make people ill. All of these factors mean that many centuries ago people in these countries worked out that pigs equals ill health and shouldn't be eaten - it got woven into the religion and is maintained today.

I think the thing with catholics and fish is sort of similar, in that the fishermen went out on monday's to get the fish and came back on friday so it was eaten on friday when it was at its freshest - this too got woven into the faith over the centuries.