This is the live question, and the Assembly is the clearest natural experiment anyone has run on it. Growth was extremely fast — from one room in Islington in January 2013 to dozens of cities within two years, with around seventy chapters at the peak — and the contraction was almost as fast, with roughly half closing or going dormant and forty-eight locations recorded as of December 2019. Part of the New York branch split away early, wanting more emphasis on atheism than the founders were comfortable with, and New York assemblies stopped organising in 2016. The structural diagnosis offered by both supporters and critics is the same: a congregation held together only by a running order depends entirely on two or three volunteers per city, and when they burn out there is no doctrine, no clergy and no obligation to bring anyone back.