How is it that a person's theology changes so much depending on whether they want to justify their hatred of homosexuals or justify the clothes they want to wear or the food they want to eat?

Could it be the weather, Martin?  Ever tried wearing sandals in the Arctic, or a heavy parka in the rain forest?  Or perhaps its the proximity to the sea - shellfish can be difficult to get in the middle of a continent.  Perhaps its the ability to cook efficiently; ever tried cooking sausages on a luke-warm fire?

It ids interesting to look at the foods, for instance, that God is said to have told the people of Israel not to eat.  Pork and other similar meats are well-known for being very hard to cook and for having unpleasant side-effects if eaten when not properly cooked.  Similarly, shellfish are known to ingest toxins and other unpleasant things which need very careful cooking to ensure their safety to eat.

Now, those are all scientifically-proven for us in the 20th/21st century?  Perhaps God knew something that we don't - or that the Jews certainly didn't.

It might also have something to do with the way in which God seems to have instructed Peter that some of the old dietary rules were now obsolete - or had you forgotten that?