Churchgoers are moving from mainline Christian denominations to more extreme evangelical or fundamentalist denominations. Evangelicals have become a majority of all Protestants [1]. Generalizing, these churches are stridently political in character, and often have social beliefs unacceptable to most of us.
What we are seeing is many churches having reoriented themselves with respect to society: while before they were community meeting places in areas with nearly identical backgrounds and beliefs, now they define themselves in opposition to a diverse community and the changes it brings.
In other words, it's not just that people have abandoned churches (secularization); it's also that many churches have self-consciously abandoned their roles as third places.
[1] https://www.pewforum.org/2015/05/12/chapter-1-the-changing-r...