The introduction sets out the context, aims and approach of this book. It explains that over the past thirty years, the number of cases before the ECtHR concerning freedom of thought, conscience and religion has increased significantly and interest in this right in the literature has grown exponentially. It notes that ECtHR jurisprudence relating to ECHR Article 9 has been heavily criticised by commentators but there has been very little interrogation of the core premises that underpin doctrinal analyses of Article 9 in recent years. In particular, the fundamental question—what is the law in relation to freedom of religion or belief?—has not been fully explored. The introduction explains that this book aims to address this important question in relation to ECHR Article 9 and, in doing so, it challenges the classic approach to freedom of thought, conscience and religion in the literature and offers an alternative interpretation of ECHR Article 9 and the related ECtHR jurisprudence. The detailed overview of the structure of this book in the introduction details the approach which will be taken, and sets out the the materials which form the basis for the analysis.