linguistic:voice_change, information:extraction
Reorganization (1917–1942)

In January 1917, the Watch Tower Society's legal representative, Joseph Franklin Rutherford, was elected as its next president. His election was disputed, and members of the Board of Directors accused him of acting in an autocratic and secretive manner. The divisions between his supporters and opponents triggered a major turnover of members over the next decade. In June 1917, he released The Finished Mystery as a seventh volume of Russell's Studies in the Scriptures series. The book, published as Russell's posthumous work, was a compilation of his commentaries on the Bible books of Ezekiel and Revelation with numerous additions by Bible Students Clayton Woodworth and George Fisher. It strongly criticized Catholic and Protestant clergy and Christian involvement in the Great War. As a result, Watch Tower Society directors were jailed for sedition under the Espionage Act in 1918 and members were subjected to mob violence; the directors were released in March 1919 and charges against them were dropped in 1920.

Rutherford centralized organizational control of the Watch Tower Society. In 1919, he instituted the appointment of a director in each congregation, and a year later all members were instructed to report their weekly preaching activity to the Brooklyn headquarters. Significant changes in doctrine and administration were regularly introduced during Rutherford's 25 years as president, including the 1920 announcement that the Hebrew patriarchs (such as Abraham and Isaac) would be resurrected in 1925, marking the beginning of Christ 's thousand-year earthly kingdom.

Because of disappointment over the changes and unfulfilled predictions, tens of thousands of defections occurred during the first half of Rutherford's tenure, leading to the formation of several Bible Student organizations independent of the Watch Tower Society, most of which still exist. By mid-1919, as many as one in seven of Russell-era Bible Students had ceased their association with the Society, and as many as three-quarters by the end of the 1920s.

On July 26, 1931, at a convention in Columbus, Ohio, Rutherford introduced the new name Jehovah's witnesses, based on Isaiah 43:10: "'Ye are my witnesses, saith the Lord, and my servant whom I have chosen: that ye may know and believe me, and understand that I am he: before me there was no God formed, neither shall there be after me'" (King James Version). It was adopted by resolution. The name was chosen to distinguish his group of Bible Students from other independent groups that had severed ties with the Society, as well as to symbolize the instigation of new outlooks and the promotion of fresh evangelizing methods. In 1932, Rutherford eliminated the system of locally elected elders and in 1938, he introduced what he called a theocratic (literally, God-ruled) organizational system, under which appointments in congregations worldwide were made from the Brooklyn headquarters.

From 1932, it was taught that the "little flock" of 144,000 would not be the only people to survive Armageddon. Rutherford explained that in addition to the 144,000 anointed who would be resurrected—or transferred at death—to live in heaven to rule over earth with Jesus, a separate class of members, the "great multitude", would live in a paradise restored on earth; from 1935, new converts to the movement were considered part of that class. By the mid-1930s, the timing of the beginning of Jesus' presence (Greek: parousía), his enthronement as king, and the start of the last days were each moved to 1914.

As their interpretations of the Bible evolved, Witness publications decreed that saluting national flags is a form of idolatry, which led to a new outbreak of mob violence and government opposition in the United States, Canada, Germany, and other countries.