The Christian Church in Sumba works on the island of Sumba in Indonesia. It was founded in 1947 and is a member of the Reformed Ecumenical Council. It branched out and developed from the missionary work of the Protestant Church in the Netherlands. It has 124 ministers assisted by over 200 evangelists and lay preachers. There are 109 congregations with close to 350,000 members. The Christian Church of Sumba also ordains women, 38 of the current pastors are women.

In 2005, The Christian Church of Sumba developed a new evangelist training school. They also run primary, secondary and tertiary schools as well as two hospitals and welfare and development programs. The Christian Church of Sumba is organised according to the Presbyterian-synod tradition with a synod as the supreme governing body. Evangelism is one of its main priorities. The churches meet every four years. They have adopted the Holy Scriptures and the Heidelberg Catechism as their doctrine.