term 'new religions' would virtually replace the term 'cult' to describe all of those leftover groups that did not fit easily under the label of church or sect." Sociologist Amy Ryan (2000) has argued for the need to differentiate those groups that may be dangerous from groups that are more benign. Ryan notes the sharp differences between definitions offered by cult opponents, who tend to focus on negative characteristics, and those offered by sociologists, who aim to create definitions that are value-free. The movements themselves may have different definitions of religion as well. George Chryssides also cites a need to develop better definitions to allow for common ground in the debate. Casino (1999) presents the issue as crucial to international human rights laws. Limiting the definition of religion may interfere with freedom of religion, while too broad a definition may give some dangerous or abusive groups "a limitless excuse for avoiding all unwanted legal obligations." New religious movements A new religious movement (NRM) is a religious community or spiritual group of modern origins (since the mid-1800s), which has a peripheral place within its society's dominant religious culture. NRMs can be novel in origin or part of a wider religion, in which case they are distinct from pre-existing denominations. In 1999, Eileen Barker estimated that NRMs, of which some but not all have been labelled as cults, number in the tens of thousands worldwide, most of which originated in Asia or Africa; and that the great majority of which have only a few members, some have thousands and only very few have more than a million. In 2007, religious scholar Elijah Siegler commented that, although no NRM had become the dominant faith in any country, many of the concepts which they had first introduced (often referred to as "New Age" ideas) have become part of worldwide mainstream culture. Scholarly studies Sociologist Max Weber (1864–1920) found that cults based on charismatic leadership often follow the routinization of charisma. The concept of a cult as a sociological classification, however, was introduced in 1932 by American sociologist Howard P. Becker as an expansion of German theologian Ernst Troeltsch's church–sect typology. Troeltsch's aim was to distinguish between three main types of religious behaviour: churchly, sectarian, and mystical. Becker further bisected Troeltsch's first two categories: church was split into ecclesia and denomination; and sect into sect and cult. Like Troeltsch's "mystical religion", Becker's cult refers to