Crime is not as high per capita as in the 90's.
Link Edit: that is for the US. I don't know what it is in the UK.
The increased prevalence of mental health issues is because we have become more aware of them and don't sweep them under the rug as much. And knowing about mental health issues is good, we need to work on helping people with them and not just accommodating them. I see that as a good thing.
It always seems like something is deteriorating, but sometimes what is deteriorating needs to change to improve. It may not seem like an improvement to those who benefited from the way it was, but change is needed to help more people, not just a few.
But it is growing in the rest of the world. Why be Western-focused on this? In the West, Christians are not persecuted, hunted, or physically harmed like in other places. The decline is due to two things from my viewpoint. The first is tying Christianity to politics. The second is a lack of cultural dominance of Christianity and cultural acts that focused on that. There are fewer people in the church because they don't feel the need to go to fit in or be protected.
Whether this is a good thing or not we will see.