Archimandrite Tikhon Shevkunov is head of the Sretensky Monastery in Moscow and the author of a best seller on monastic life.Credit...Dmitry Kostyukov for The New York Times MOSCOW — As the Russian Orthodox Church continues its ascent as a political force, Archimandrite Tikhon Shevkunov stands at the center of a swirling argument about the church’s power and its possible influence on President Vla