From 1649 he had the opportunity to study abroad and was enrolled at the universities of Leiden, Leipzig and Orléans.

He served as Bishop of the Diocese of Oslo (Akershus stift) from 1664 until his death in 1699.

He also collaborated closely with Viceroy (Statholder) Ulrik Frederik Gyldenløve (1638–1704) who was Governor-general of Norway.

Additionally he arranged for the construction of Vår Frelsers kirke (now Oslo Cathedral).

[3][4] Rosing was married twice; 1st with Gertrud Hansdatter Borchardsen (1636-1660), 2nd with Kirsten Bang (ca.