Bishop Koltun was born in the family of clandestine Greek-Catholics Pavlo and Stanislava (née Kret) Koltun. After graduation of the school education, he graduated the college of industrial automation in Lviv and made a compulsory service in the Soviet Army. Then he worked in the concrete products plant from 1972 until 1989.[1]
During all this time he was clandestine member of the Congregation of the Most Holy Redeemer, where he had a profession in 1975 and a solemn profession on 8 November 1981. Koltun was ordained as priest on 13 December 1981, after completing clandestine theological studies.[1] From 1990 until 1993 he openly served as priest, missionary and founder of the new Greek-Catholic parishes.[1]