In short, religious belief, and the importance that people attach to those beliefs, has declined just as fast as attendance and affiliation. The counter-argument is that unorthodox belief – in everything from angels to zombies – seems to have held up quite nicely. For the most part, though, these “beliefs” are casual in the extreme: cultivated by popular culture and its delight in magic and Gothic romanticism, held in the most tentative and experimental way, with no connection to any meaningful spirituality.
Supernaturalism has certainly not disappeared, but for the white British (as for the populations of highly developed countries generally) it is becoming less and less salient. Immigration and geopolitical tensions have partially revived the social significance of religion, but there are few signs that spirituality or anything else has replaced its personal significance.
The contrast between Muslims and nominal Christians is instructive. Most Muslims go for an entire month each year without consuming food or drink during daylight hours; most are lifelong abstainers from alcohol. In addition, many Muslim women defy mainstream cultural convention by covering their heads. Some may feel community pressure to do these things, but many believe that God and scripture require their obedience. What are Christians willing to do for God? Not enough, perhaps, to keep the faith alive.