Since the founding of the Council of Churches in Indonesia (DGI), which later changed its name to the Communion of Churches in Indonesia (PGI), a recurring question has been asked about what kind of unity the DGI/PGI intends to achieve. This issue was discussed by the General Assemblies, from the first in 1950 until the 10th in 1984, with various ideas being put forward. Some underscored the unity of structural organisations, whereas others emphasised our spiritual unity in Christ. It was only at the 10th General Assembly held in 1984 at Ambon that Indonesian churches discovered the answer they had been seeking all that time. The unity they sought was a shared understanding of Christian doctrine, mutual recognition and acceptance, and co-operation in working together to carry out their task and calling in Indonesia. In this respect, I believe that the view of Indonesian church unity conforms to Calvin’s concept which does not stress organisational unity but rather spiritual oneness, oneness in Christ, and oneness in the basic principles of the faith, in recognising each other as having the true preaching of the Word and administration of the sacraments. It is this kind of unity which has been expressed in the Five Documents of Church Unity (LDKG), later called Documents on Church Unity (DKG). The churches of Indonesia can learn much from the view of church reformer John Calvin.