He was born in
Selbu Municipality in
Trøndelag, Norway. He was the son of Peder Einarsen Amdahl (1863–1942) and Marit Bardosdatter (1862–1942). He was raised in a
Haugean movement home. He attended
Hans Nielsen Hauge Minde in
Kristiania and graduated in 1910. He was ordained a priest in 1916 and was called to the newly created position of assistant secretary general of the Norwegian Missionary Society (
Det Norske Misjonsselskap). He served as secretary-general for the society from 1923. Amdahl resigned from his office in 1957 to be replaced by
Fridtjov Søiland Birkeli. During the
German occupation of Norway, he participated in the
Norwegian resistance movement, and served in an internment camp from June 1944 until the end of
World War II. He was decorated Knight, First Class of the
Order of St. Olav in 1963. ==References==