August Theis led a group of
German missionaries to spread Christianity to the Simalungun area after he received a telegram from the local Rheinische Missionsgesellschaft (RMG - Deutschlands-based sending institution) leader. On 2 September 1903 they arrived at
Pematang Raya to begin their mission among the Simalungunese. 2 September has been celebrated each year by GKPS all over the world as an
olob-olob (Simalungunese for joyous) day to thank God that the
Bible has entered Simalungun. The sending mission was effectively started in 1904 with August Theis at Pematang Raya and Guillaume at Purba Saribu (western part of Simalungun). Not until 1909 did the first Simalungunese Christian baptism occur at Pematang Raya. Later in the same year, 38 other Simalungunese were baptized at
Parapat. Up to 1910, 17 churches were founded inside the Simalungun area. They were: •
Tigaras, 15 August 1903 •
Tinjoan, 15 August 1903 •
Pematang Raya, 2 September 1903 •
Raya Usang, 8 September 1903 •
Dolok Saribu, 14 September 1903 •
Bulu Raya, 16 June 1904 •
Purba Saribu, June 10, 1905 •
Haranggaol, 3 March 1906 •
Raya Tongah, 7 June 1906 •
Purba Dolok, 15 August 1906 •
Pamatang Purba, 15 August 1906 •
Purba Tongah, 1906 •
Hinalang, 8 September 1908 •
Kariahan, 1908 •
Saribudolok, 6 September 1909 •
Tambun Raya, 2 November 1909 The first missions were held using the
Toba language. Simalungunese resistance to the Westerners and their lack of comprehension of the Toba language decreased RMG effectiveness and therefore held back the growth of Christianity among the Simalungunese. On 1 September 1928, the celebration of the 25th anniversary of Christianity at Simalungun was held at Pematang Raya. On this occasion, some Guru (teachers) and Sintua (deacons) agreed to found a committee which planned to translate church-related text books into the Simalungun language. This produced Haleluya (singing book) and Manna (daily reading book). On 15 November of the same year, a group called "Kongsi Laita" (laita means "let's go") was founded at Sondiraya by some members of the Pematang Raya church to ask the Simalungunese to spread Christianity by themselves to others. ==Simalungun District inside HKBP Simalungun==