Who was Archimandrite Spiridon?

This article by Father Antoine Lambrechts, a monk of Chevetogne, offers a biographical and theological study devoted to Archimandrite Spiridon Kislakov (1875-1930), author of the celebrated *Missions en Sibérie* translated into French by Pierre Pascal in 1950. Drawing on a long-inaccessible work, the *Confession of a Priest before the Church* (Kiev, 1919), which remained unknown throughout the entire Soviet period, the article reconstructs the identity, life journey, and thought of this missionary monk who came from the common people. The study shows that Spiridon cannot be reduced to a mere witness of Russian popular religiosity: he represents an evangelical current of pastoral renewal within the pre-revolutionary Russian Orthodox Church, marked by a radical evangelical pacifism and a critical ecclesiology. The principal contribution of the article is to shed light, through previously unpublished sources, on the spiritual and ecclesiological significance of a work that had until then been poorly understood.