Bishop Hilarion (Belsky) was born on March 20, 1893 (according to other
sources, between 1896 and 1898) in the family of a Petrograd protopriest in
Olonets province. He finished his studies at Olonetsk theological seminary in
1915 and entered the Saint Petersburg Theological Academy and the brotherhood
of the Alexander Nevsky Lavra, where he was tonsured into the mantia on July
3, 1919, ordained to the diaconate on July 13, 1919, and to the priesthood in
1922. He showed great firmness in the struggle against renovationism in
Petrograd. In June, 1922 he was arrested in Petrograd and released shortly
afterwards. In September, 1924 he was raised to the rank of igumen.
On October 1/14, 1924 Patriarch Tikhon consecrated him Bishop of Kargopol, a vicariate of the Olonets diocese, although he was only 30 years old. From 1924 he was in exile in Smolensk. On April 12, 1925 he signed the act transferring leadership of the Church to Metropolitan Peter. Later, for one year and eight months from 1926 to 1927, he administered the Smolensk diocese, being commemorated as bishop of Porech, a vicariate of the Smolensk diocese. According to one source, he was Bishop of Kotelnich in 1927.
He was an opponent of Metropolitan Sergius' declaration, and joined the "Victorian" branch of the Catacomb Church on February 20, 1928. [This branch, led by Hieromartyr Victor of Vyatka, joined the Russian Orthodox Autonomous Church in the 1990s.] In April, 1929 he was arrested and sentenced to five years in the camps, which he served on Solovki. He was one of those who were forbidden from working in their specialism, and had to do the heaviest manual labour.
On October 1,1929, under pressure from the sergianist bishops, he served in the cemetery church, commemorating the name of Metropolitan Sergius. What happened next was described by Hieromartyr Nectarius, Bishop of Yaransk, his fellow-prisoner on Solovki, who heard it from Vladyka Hilarion himself: "Shortly before this [service in the cemetery church], he had a very frightening dream. It was as if he trampled the Smolensk Hodigitria icon of the Mother of God under foot. And what then? After serving the liturgy with the sergianist bishops, instead of receiving spiritual consolation and joy, he began to feel terrible pangs of conscience and depression of spirit, 'and the sergianist apostasy,' he told me, 'became quite clear to me - I had turned out to be a participator in the sergianist crimes against the Orthodox Church.' And what then? At that very moment he declared to the sergianist bishops that he was leaving them and returning to his former ecclesiastical position with Bishops Victor, Nectarius, Demetrius and the others."
In September, 1931, he, together with Archbishop Seraphim of Uglich and Archbishop Pachomius of Chernigov, was sent to work on the White Sea canal. In 1933 he was released and exiled to Kosmodemyansk, Mari ASSR. From 1935 to 1937 he was in exile in Cheboksary, where he served in secret. He did not recognize the sacraments of the sergianists, and used to repeat the sacraments of baptism and marriage performed by sergianists. In the summer of 1937 he visited Bishop Sergius (Druzhinin) in exile and urged him to remain faithful to Orthodoxy. In August he was arrested and sent for interrogation to Yoshkar-Oly. On August 31, 1937 (new style) he was sentenced to be shot. The sentence was carried out the same day.