"Protestantism is traditionally understood to designate the churches and denominations that have received their inspiration from the Reformation, including the whole unfolding of that history from the sixteenth century down to the present day. This understanding of the notion informs this ‘’Companion’’, which aims to explore the many facets of this development, especially within Western culture. Yet it must be conceded that ‘Protestantism’ remains obstinately resistant to more precise definition. As by far the most diverse form of contemporary Christianity, it is more susceptible to description rather than definition. Its intrinsic resistance to any concept of centralized authority corresponding to the Roman Catholic magisterium had led to a remarkable degree of diversification at both the theological and sociological levels. Even though certain important patterns of commonality may be discerned, contemporary Protestantism is perhaps at least as notable for its divergences as for its shared historical roots and theological agendas. The rapid growth of Protestant denominations in the twentieth century, given further impetus through the remarkable development of charismatic and Pentecostal groupings, has made it increasingly difficult to speak convincingly to the ‘essence of Protestantism’. While there are important debates within the movement over what its core identity and values might be, empirical observation of the movement suggests that the self-understandings of the movement have become increasingly fluid since the Second World War. The rapid expansion of the movement in its Pentecostal and charismatic forms, particularly when set against the backdrop of the decline of traditional Protestant denominations in the West, suggests that the profile of Protestantism is likely to undergo highly significant changes in the twenty-first century. In recent times, ‘Protestant’ has increasingly become a shorthand term for a number of seemingly disparate Christian denominations and general cultural attitudes, which need to be parsed carefully. Even its more notorious and disparaged nonreligious caricatures contain at least some trusts about the nature of the movement. Thus Friedrich Nietzsche, Max Weber and H. Rich Niebuhr argued that ‘Protestantism’ designates an ethos that has certain specific political and economic overtones, namely those associated with Western European capitalism and politics and present-day American-style democracy. All argue with differing stresses that there are specific ideas, disguised and given authority as specific doctrines, inherent in the mainline or ‘magisterial’ Reformation that were and are catalytic to forms of the modern Western world and which have also contributed much of the woes of that culture. The commonality is the stress of the ideological penetration, usually thought of as negative, embedded in its theology, of Protestantism in the nontheological (or seemingly so) areas of politics, culture and economics."