While Charles I's wife was Catholic, he wasn't, so I'm not sure which "one catholic king" England executed. He was certainly more tolerant of the Catholic viewpoint than many at the time, but that's not actually the same as being Catholic.

I'm not a historian either, but I'd be pretty confident that the historical troubles (and 1666 in particular) were much more about which local bigwigs and claimants had power over what than really Protestant-vs-Catholic. That is, the l.b's wouldn't have many qualms about enlisting/demonising the Catholic Church/Spain/The Netherlands/Uncle Tom Cobley to further their personal ends rather than for some abstract greater good.

It's how we behave now, and I very much doubt that we've ever behaved very differently (except for rare cases here and there.)