In 1932, Ratulangi was one of the founding members of the United Scholars of Indonesia ("Vereniging van Indonesische Academici"). He was also part of a group of church leaders and nationalists (including B.W. Lapian and A.A. Maramis) who wanted a church denomination that was free and separate from the official church institution of the Dutch East-Indies (called "Protestantsche Kerk in Nederlandsch-Indie" or "Indische Kerk"). In March 1933, the independent Convention of Protestant Churches in Minahasa (KGPM or "Kerapatan Gereja Protestan Minahasa") was established.