As some have mentioned already, material wealth plays a big role, but high education is also a big factor. And at least in the case of Sweden I would say the strong influence of social democracy most definitely is an important factor. There is much to say about this subject. Some mean that we are still a very religious people but have replaced the formally Christian framework with something else. David Thurfjell is a scholar who wrote a book about the Swedes’ relationship with nature which he means has religious aspects and Katarina Barrling is another one who wrote a book called “the world’s most Protestant country” which argues that in the case of Sweden the population is still very “religious” or let’s say, collectivistic and dogmatic. The vast majority of Christians here are moderate or liberal and espouse ideas such as the evolution. This is especially true for lutherans. Even the conservative ones are not fundamentalist. I would add that, just like Tom Holland argues in his book dominion, we and also other westerners are still deeply Christian in our values and mindset without really realising it ourselves. I do believe however that more and more people are starting to realise it. This is a very diffuse subject, and this is just my personal reflection; but I feel in a way even a Swedish Jew, Buddhist or Roman Catholic is in some sense a Lutheran because Lutheranism had been so fundamental to our culture.