Rutherford wrote many books as well. He made some changes to Russell's teachings and required all the study groups, or congregations, around the world to agree to the teachings and rules set by the Watch Tower Society in New York. He told members not to celebrate holidays, and they should not sing at religious meetings. He also told them to preach from door to door about God's kingdom and to sell Watch Tower Society publications so more people would hear the message. Many members did not agree with Rutherford's strict changes, and some started their own groups. In 1931 Rutherford called his group "Jehovah's Witnesses" to tell it apart from the other groups. By the time Rutherford died in 1942, the religion had a worldwide membership of 115,000.