Walter Bonar Sidjabat was born on October 19, 1931 as a son of a headmaster in the rural area of North Sumatra, Having studied for two years in the rural area, he entered a Dutch speaking school in Pematang Siantar. World War II introduced him to JapaneseC language and various experiences during the Occupation. While studying in a techno-logical school the Indonesian Revolution took place. He then entered the Students Army as a consequence of which he had to evacuate to the Republican region during the Dutch Military Action 1 & 11 (1947 and 1948).

The socio-political changes that took place during the critical periods of Indonesian history, did not prevent him to learn much from books and experiences, Serious efforts on his part after the acknow-ledgement of the Indonesian Independence by the Dutch in 1949, made it possible for him to finish his theological education in Jakarta as early as November 1955. This in turn opened the door for studying at Princeton (USA) both at the Seminary as well as at the University in which he earned his Th.M. (1957) and Ph.D. (1960).

Having worked in Geneva for a couple of months he returned to Jakarta and lecturing at the Jakarta Theological Seminary (STT) on Islamics. While serving as the Research Secretary of the Council of Churches in Indonesia (DGI) for twelve years (1960-1972), he was also working as Editor in Chief of a Magazine, Ragi Buana (1964-1973). At present, while continuing his main joh as Professor of Religion and Society at STT Jakarta, he is function-ing as Editor in Chief of Penerbit Sinar Harapan.