in the uk? the anglican church. generally in the west? whatever lutheran, protestant, or catholic denomination is approved by the state. generally? the main church of that country, which for most of them is in a 90/10 sort of situation, with some notable exceptions, like the us, which shouldn't be counted because a) it's such a small part of the world's population and b) their view of religion is so screwed up that it doesnt compare to anything.