At the beginning of the seventeenth century the doctrine of the Trinity was still a central theme in Christian Theology. By the end of the century it was fast becoming peripheral. As theologians today increasingly recognize the Trinity to be at the very heart of the Christian theology, the question of ''what went wrong'' three hundred years ago is a matte of growing interest. Whereas most studies of the history of tinritarian doctrine neglect the seventeenth century almost entirely, Philip Dixon argues that this is a key period in the history and development of the doctrine and, indeed, essen