I'm not sure what it's like in the US, but I feel like the UK protestant churches have an unseriousness about them. Like they've consulted a social media manager for an illinformed rebranding and been told that Pinterest live laugh love aesthetics and liberalism will draw in the crowds. I may just be basing this on a few churches I walk past, in quite affluent liberal areas lol).

(Not sure in what sense you are using mysticism here(?) but there is a level of seriousness in the Christian mystics which I find more appealing than the Protestant approach.)