Eidsvig was born and raised in Rjukan, Norway. He studied theology at the University of Oslo and planned to become a minister of the Norwegian Church. He took a theological degree there with the church's historic special task of Church and Society in the Chronicles of Barsetshire, a series of six novels by the English writerAnthony Trollope. He also worked for ten years as a freelancer for the newspaper Morgenbladet. He converted to Catholicism on 20 December 1977.
On 14 July 1976, Eidsvig was arrested by the KGB in Moscow while he was acting as a courier for the exiled Russian organization National Alliance of Russian Solidarists. His mission was to deliver leaflets, renal medicine and a handbook of "rebellion" to a Soviet Russian in Moscow who had requested these supplies. The intended recipient had been betrayed and arrested. When he arrived to make the delivery he was arrested by agents of the KGB and was held in Lefortovo Prison for 101 days, when Norwegian Foreign MinisterKnut Frydenlund and Prime Minister Trygve Bratteli won his release. The arrest attracted considerable attention both in Norway and internationally, much of which was negative. While he was still in prison, some reports–influenced by Soviet disinformation–made his efforts look foolhardy, even reporting that he had been handing out fliers on the street in Moscow. The Soviets used clippings of this sort from the Norwegian press, including the coverage in Aftenposten, to weaken his resistance under interrogation.
Clerical career
After completing licentiate studies at Heythrop College in London, Eidsvig was ordained as a priest of Oslo Catholic Diocese of St. Olav's Cathedral in Oslo on 20 June 1982 by John Willem Gran, Bishop of Oslo. He served for a time in the military chaplain corps of the Norwegian Armed Forces, partly at Evjemoen north of Kristiansand and partly with the medic recruits' company in Bømoen by Voss. He then served as chaplain at St. Paul's in Bergen and on 1 January 1986 became pastor there. While pastor, he moved and expanded the Catholic school St. Paul Bergen. He was also a teacher at the school and was active in the language association Riksmålsforbundet. In the Catholic Diocese of Oslo, he served on the Priests' Council from 1983 to 1990, the Consultors' Council from 1987 to 1990, and the Pastoral Council from 1988 to 1991. In the summer of 1991, Eidsvig was received as a novice by the Canons of Stift Klosterneuburg in Austria, just outside Vienna. He was invested with the religious habit on 27 August 1991, and received the name Mark. He made his profession of vows on 30 August 1995. He then worked from 1997 to 2003 as pastor of St. Leopold's Church in Klosterneuburg, and from 1996 at the monastery as master of novices. Under his leadership of the novitiate, the Stift Klosterneuburg took on a more international flavor, welcoming candidates from the United States, Germany, Norway, and Vietnam, the last by way of Norway as refugees. He has also been chapter counselor and chapter secretary of the Stift.
Bishop
appointed Eidsvig Bishop of Oslo on 11 July 2005. The announcement was delayed to the symbolic date of 29 July, the memorial day of Norway's patron saint, St. Olav. Eidsvig was the first Canon of Klosterneuburg to be appointed bishop since 1913, when the monastery Pastor Friedrich Gustav Piffl was appointed Archbishop of Vienna. On 22 October 2005, he received his episcopal consecration in the Lutheran Trinity Church, opened to the Catholic community by the Norwegian Church for the occasion, and then was installed in St. Olav Cathedral. The consecration mass was broadcast on the Internet via www.katolsk.no. Eidsvig is the third Norwegian-born Catholic bishop in Norway since the Reformation, after Olaf Offerdahl and John Willem Gran. He has also been a staff member of the Catholic journal St. Olav. He was named Apostolic Administrator of the Territorial Prelature of Trondheim on 8 June 2009, upon the resignation of Bishop Georg Müller, which in 2010 he explained had come as the result of a charge of child sexual abuse against Müller. His term as Apostolic Administrator ended in October 2020 with the consecration of the new Bishop–Prelate of Trondheim.
Fraud charge
On 26 February 2015, Eidsvig and the financial manager of the Catholic Diocese of Oslo were charged with felony fraud, after the diocese was reported on suspicion of registering people as members of the Roman Catholic Church in Norway without their knowledge or consent. Charges were also made against the diocese itself, covering several years of fraudulent membership claims resulting in grants of from the Norwegian government. The charges against Eidsvig were dropped in November 2016 when the other parties were brought to trial.
Coat of arms
Eidsvig coat of arms as a bishop is divided into four fields. 1. and 4 field, Oslo Catholic bishop arms, while the other two have half the arms of Klosterneuburg combined with the flowering rod of Aaron. Klosterneuburg arms are divided according to the rule that only the abbot can use all the arms, while the bishops who belonged to the monastery uses half combined with another emblem. The shield is crowned with a green "prelathatt", which is a "galero" in Italian, with six green tassels on each side of a bishop's cross. His motto is Labori non Honori, "work, not honor." It's the same motto as cardinal Piffl, Archbishop of Vienna, elected in 1913, it is the beginning of a motto in its entirety which reads "work, not honor, to my effort to be devoted." This is a reproduction of this sentiment expressed in St. Augustine's writings.