Sociologist James A. Beckford, in his 1975 study of Jehovah's Witnesses, classified the religion's organizational structure as Totalizing, characterized by an assertive leadership, specific and narrow objectives, control over competing demands on members' time and energy, and control over the quality of new members. Other characteristics of the classification include likelihood of friction with secular authorities, reluctance to co-operate with other religious organizations, a high rate of membership turnover, a low rate of doctrinal change, and strict uniformity of beliefs among members. Beckford identified the religion's chief characteristics as historicism (identifying historical events as relating to the outworking of God's purpose), absolutism (conviction that Jehovah's Witness leaders dispense absolute truth), activism (capacity to motivate members to perform missionary tasks), rationalism (conviction that Witness doctrines have a rational basis devoid of mystery), authoritarianism (rigid presentation of regulations without the opportunity for criticism) and world indifference (rejection of certain secular requirements and medical treatments).