Nonni was born at Möðruvellir in Hörgárdalur on the 16th November 1857 and was raised there until the age of seven. His parents were respectable people and gave their children a good Christian upbringing. In the year 1865, Nonni moved with his family to Akureyri in a little black woodhouse which today is called "Nonni´s house". Nonni´s father died when Nonni was eleven years old. The times were difficult and it was too much for his mother to support herself and her children.
Nonni went abroad in the year 1870, twelve years old, when a French nobleman offered to pay for his education in France. Because of the war in Europe at that time, he spent a year in Denmark, where he became a Roman Catholic before he went to France. In France, Nonni studied at The Latin school in Amiens. Nonni´s younger brother, Manni, began his studies at the same school as Nonni. Manni died young, only 23 years old.
Nonni finished his studies at the Latin school and became a member of the Jesuit order in the year 1878. He studied at a university level for five years in France, Belgium and Holland and read literature, philosophy and theology. In 1883, Nonni became a teacher at a Catholic school in Ordrup in Denmark were he worked the next 20 years.
In 1912, Nonni gave up teaching due to illness After that he wrote books and gave lectures around the world. He delivered altogether about 5000 lectures and wrote 12 books. His books have been translated into app 40 languages.
Nonni died in Cologne in Germany in Oktober 1944 at the age of 86.