This church grew out of a spiritual, congregational reform movement in the Batak Protestant Christian Church (HKBP) which led to a split due to some disagreement in the leadership. The GKPI was established in 1964. The first years were difficult because the church had no relationships locally and internationally. Its membership increased and the isolation was overcome when the church joined the Lutheran World Federation and the United Evangelical Mission in 1977. The GKPI is a national church which has spread around Sumatra, to Java and Kalimantan, but its members are mainly of the Toba-Batak ethnic groups and its geographical concentration is in North Sumatra. More than 75 percent of the members are small farmers living in the villages and rural areas. Others are in government service or in the military, or are shop-holders, beçak drivers, etc. Most of them belong to the low income group with few skills to improve their living conditions.

The GKPI has three departments, for witness, general organization and finance, under which several sections deal with programmes like evangelization, training and education, Sunday school, research, youth, women, men etc. There are also some foundations, for the blind, for general education, the Mamre Orphanage and the Agapè Foundation. The work depends on the financial support of the congregations, which are also responsible for the salary of their parish pastor. Some of the programmes are also supported by the United Evangelical Mission. The GKPI is in favour of the type of partnership promoted by UE, because it helps the churches to know each other’s conditions, needs and challenges, and to learn from each other how to implement the mission of Jesus Christ in the world, and it enables the churches to carry out their ministry. Among the priorities of the church are the training of pastors, elders and church leaders to develop their knowledge, skills and leadership abilities, and to deepen their spiritual life and dedication. The GKPI has encouraged a number of pastors to do post-gradu-ate studies. The church is also planning a cooperative budgeting system for its activities, aiming at local fundraising and financial self-reliance.