Query: What does Lawson suggest has contributed to the consistency of the sense of urgency in Jehovah Witnesses' apocalyptic message?
Context: Jehovah's Witnesses see themselves as a worldwide brotherhood that transcends national boundaries and ethnic loyalties. Sociologist Ronald Lawson has suggested the religion's intellectual and organizational isolation, coupled with the intense indoctrination of adherents, rigid internal discipline and considerable persecution, has contributed to the consistency of its sense of urgency in its apocalyptic message.