Call it what you like: bums on pews, Fresh Expressions, the crisis of Christianity/religion.
Why don't people come to church any more?
My own theory is simple and probably not very helpful. I think that people don't come to church any more because people don't want to join groups. Still less do they want to join institutions. Ask the Scouts, the Toastmasters or the Rotary. It's not like people are flocking to join these groups whilst studiously avoiding the church. I think that this is a sea-change in our culture and it's a change that is very difficult for the church in general even if individual congregations are able to attract numbers.
I'm not of the view that people don't come to church any more because they are more hostile to religion or to Christianity than they were in the past. In this, I disagree with a lot of my friends in 'real life'.
My disagreement comes from my past when I had an 'office job' and people were constantly askimg me about God and constantly wanted to talk about God. People are, I think, quite interested and eager to talk about God as long as they don't have to come to church.
Let's be honest. In the days of the 'church as a bulwark of general society' church was about individual congregations being essentially local clubs. What is church in this new cultural context where few want to join a club but many want to talk about God?
As usual, I have no easy answers. I wish I did!