The paper proposes the concept of an Ecumenical Filocalia for the Anthropocene as a heuristic framework for rearticulating Christian spiritual resources in late modern contexts marked by fragmentation, ecological crisis, and weakened institutional authority. Rather than reconstructing the Filocalia as a devotional anthology, the paper interprets it as a curated repertoire of spiritual grammars capable of shaping interiority and relational personhood beyond confessional boundaries. The proposed core of the Ecumenical Filocalia draws on a historical-theological constellation of formative voices: Augustine's theology of interiority (interior intimo meo), Aquinas's integration of grace and reason, John Henry Newman's account of the reception of truth in conscience (cor ad cor loquitur, real assent), John Zizioulas's relational ontology of personhood, and Christos Yannaras's existential understanding of truth as a mode of being (tropos hyparxeos). Together, these perspectives articulate convergent patterns of Christian interior formation that resist both individualistic spiritualization and moralistic reductionism. This core is complemented by post-Reformation and publicly communicable witnesses of embodied Christian responsibility (Dietrich Bonhoeffer, Thomas Merton, Brother Roger of Taizé), indicating how interior formation may translate into forms of lived, relational, and socially credible spirituality. The constellation is not proposed as an authoritative canon, but as a Filocalia of late modern post-secular Christianity: a preliminary map of spiritual resources capable of sustaining Christian meaning-making and ethical responsibility in the Anthropocene.