Josia was the second son of the Daniel-Maria couple, two central figures described in Book I.

Josia completed his education at the Protestant Seminary at Depok, West Java as early as 1893, a very rare accomplishmentin that area.  In his young age as a Batak Mission teacher he was assigned as pioneer to take part in the missionary program of Rheinische Missions-Geselschaft called Tole den Timurland den Evangelium which was to promote teaching of the Gospel to the eastern coastal area of Northern Sumatra.  Although still a relatively junior bible tutor and teacher, Batak Mission leader, Nommensen trusted him to become the first mission teacher in the growing city of Medan in 1912.  He invited Batak youth migrants who left their home-villages to seek better living conditions in and around the city, and united them to set up an urban communion.  To up-grade this special job assignment he was ordained as minister by the Batak Mission leader, Nommensen in 1914.  It was an extraordinary and very special ordination (the first and the only in his era) considering the fact that he had never undergone any formal theological training to become minister.  Quite soon, the rapidly developed works of Minister Josia aroused jealousy and ill-feeling among senior leaders of the Batak Mission during post-Nommensen era.  He was then unintentionally trapped in a dispute for a leadership in the Batak Mission congregation which went for quite some time and marked as the first big dispute in the Batak Mission circle - and later happened once in a while within the Huria Kristen Batak Protestan (HKBP) organization.

In 1920 the sorrowful prolonged dispute resulted in the disintegration of HKBP into groups of supporters for different leaders, in different places, who later declared in their independence from the big mother-church by establishing their own smaller churches as we know them today.