Martyrdom and the Josephite separation
Bishop Sergius's death belongs to the broader history of the Russian New Martyrs, the bishops, clergy, monastics, and laity who suffered under the Soviet regime in the decades following the Revolution. His own path to martyrdom was shaped by the church-political crisis of the late 1920s, when Metropolitan Sergius (Stragorodsky) issued his declaration of loyalty to the civil authorities; a number of bishops, including Sergius of Narva, regarded this as an unacceptable subjection of the Church and separated from his administration.
After his arrest, the sources relate that he was imprisoned for five years in Yaroslavl and subsequently sent into exile in the Mari ASSR. There, in 1937 — the year of the most intense wave of executions during the Soviet terror — he was condemned to death and killed, sealing his confession of faith with martyrdom.