He has been the Bishop of Oslo since 2005 and the Apostolic Administrator of the Roman Catholic Territorial Prelature of Trondheim from 2009 until 2019.

His mission was to deliver leaflets, renal medicine and a handbook of "rebellion" to a Soviet Russian in Moscow who had requested these supplies.

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 Minister Knut Frydenlund and Prime Minister Trygve Bratteli won his release.

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.

In the summer of 1991, Eidsvig was received as a novice by the Canons of Stift Klosterneuburg in Austria, just outside Vienna.

The announcement was delayed to the symbolic date of 29 July, the memorial day of Norway's patron saint, St.

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 50 million kr from the Norwegian government.