This introduction to 'Orthodox Kaleidoscope: Heterogeneity, Complexity, and Dynamics in the Russian Orthodox Church' sheds light on its contributions from a methodological-theoretical angle. Six of the seven contributions to this issue spring from an interdisciplinary academic network established in 2015 by scholars of 15 institutions in search of approaches and theories that would do justice to the multifaceted and fluid return of the Russian Orthodox Church (Moscow Patriarchate) to society and (geo-)politics after perestroika. One of the challenges this Orthodox revival presents to scholarship is an extreme heterogeneity of groups, worldviews, and teachings, each claiming to represent 'true' Orthodoxy by virtue of their belonging to Orthodox Tradition. Such belonging grants the right to exist and exercise sacral authority on micro-, meso-and macro-levels, but also involves a non-belonging, a simultaneous insider and outsider perspective of Orthodoxy/ Orthodox Tradition. Since this problem arises in each situation when such an overreaching position (sub specie aeternitatis) is claimed, it is common to each religious tradition and is therefore pertinent to religious studies more broadly. In the Introduction I discuss this variation of Russell's paradox and the ways to overcome this conceptual problem.