Stephen Bullivant is a theologian and sociologist based at St Mary's University, UK, and the University of Notre Dame, Australia. A Catholic convert (and ex-none), his books include:The Trinity: How Not To Be a Heretic (Paulist, 2015),Mass Exodus: Catholic Disaffiliation in Britain and America since Vatican II (OUP, 2019),The Cambridge History of Atheism (CUP, 2021),Nonverts: The Making of Ex-Christian America (OUP, 2022), andVatican II: A Very Short Introduction(OUP, 2023).