Seventh-day Adventist Church in Tonga

The Seventh-day Adventist Church in Tonga, (Tongan: Siasi ʻAhofitu) is one of the smaller religious groups in the South Pacific island state of Tonga, with a reported 3,853 members as of June 30, 2020. The church was started by Seventh-day Adventist missionaries from the United States who visited in 1891 and settled in 1895. They set up schools but made very little progress in conversion, handicapped by dietary rules that prohibited popular local foods such as pork and shellfish, and that also banned tobacco, alcohol and kava.

The church was revitalized in 1912 with a renewed emphasis on evangelism. In 1922 it resumed its strategy of providing education, which resulted in an increase in conversions. After keeping a low profile during World War II (1939–45), the church grew quickly from 1950 to the 1970s. However, membership subsequently declined due to emigration and competition with other churches. The SDA of Tonga is part of the South Pacific Division of Seventh-day Adventists. It operates several schools in Tonga, and provides opportunities for further studies at Adventist institutions abroad.

Seventh-day Adventists typically observe the Sabbath on Saturdays. Tonga lies to the east of the 180° meridian, but to the west of the International Date Line (IDL), in the time zone UTC+13:00. The SDA Church determines that in Tonga the Sabbath is observed as if the IDL ran along the 180° meridian and the time zone were UTC−12:00, so it observes the Sabbath on Sundays.