His Grace Bishop Longin was born on September 29, 1955, as Momir Krco in the town of Kruscanje Olovo. His parents were Stanoje and Andja (nee Jovanovic) Krco. He attended grade school in Olovske Luke from 1962 to 1970. He entered Three Hierarchs Seminary in Monastery Krka in 1970 and graduated in 1975.

During this time he was tonsured a monk and received the small schema as a fifth-year student. The tonsuring was done by Bishop Stefan of Dalmatia on the eve of the school Slava of the Holy Three Hierarchs on February 11, 1975. At the Divine Liturgy on February 12th he was ordained a deacon by Bishop Stefan. On February 13th, he was ordained a priest.

With the decision of His Holiness Patriarch Pavle, he was appointed on July 31, 1997, as auxiliary in the administration of the Diocese of America and Canada – New Gracanica Metropolitanate. On May 23, 1998, he was appointed as Administrator of the Diocese of America and Canada -New Gracanica Metropolitanate, while on May 5, 1999, he was elected at the Holy Assembly of Bishops of the Serbian Orthodox Church, Sabor, as Bishop of the Diocese of America and Canada, New Gracanica Metropolitanate. This fulfilled the request of the Diocesan Council and the Ecclesiastical Court as well as the desire of the clergy and delegates of the Seventh Church National Sabor held on April 23 – 24, 1999.

After the administrative arrondation of our Church on the North American Continent in May 2009, a better and canonically more correct organization of our faithful people was achieved. In the same year, Bishop Longin was elected Bishop of New Gracanica-Midwestern America. Since then, His Eminence has resided in Libertyville, retaining offices at New Gracanica Monastery in Third Lake, Illinois.