This short and accessible book introduces readers to the problems of heresy, schism, and dissidence over the last two millennia. The heresies under discussion range from Gnosticism, influential in the early Christian period, right through to modern sects. The idea of a heretic conjures up many images from the martyr prepared to die for religious beliefs, through to sects with bizarre practices. This book provides a remarkable insight into the fraught history of heresy, showing how the Church came to insist on orthodoxy when threatened by alternative ideals, exploring the social and political conditions under which heretics were created, and how those involved were ‘tested’ and punished, often by imprisonmen and burning. Engagingly written, A Brief History of Heresy is enlivened throughout with fascinating examples of individuals and movements.