Digital Spiritual Formation in Post-Christian Europe: A Framework for Spiritual Formation in Digital Culture

English-speaking Bible apps pioneered digital access to Scripture, offering production quality and formats familiar from other media. YouVersion reported more than one billion cumulative installs across its family of apps in 2025. Other language communities have often received a more limited experience. Meanwhile, many spiritual apps have inherited Silicon Valley's engagement mechanics without adequately asking whether those mechanics serve formation. Growing content catalogues offer choice and recommendations, but receptive content remains largely generic. This paper examines these problems through cognitive science, behavioral data, Christian formation tradition, and the European post-Christian context. It focuses on spiritually liminal audiences: Europeans who have walked away from institutions but have not stopped seeking. Its hypothesis is that AI could support more personally responsive spiritual formation and make richer resources available to less-resourced language communities. Whether it can do so without commodifying spiritual practice or displacing human community remains an open question. The analysis develops a missional product design framework: seven principles and six diagnostic questions connecting theology to product development. Multimodal formation, resistance to spiritual commodification, grace-based mechanics, and a communal horizon constrain what responsible personalization could mean. A concluding evaluation section distinguishes business metrics from provisional formation indicators and signs of harm, and identifies findings that would count against the paper's hypotheses. The framework specifies requirements for future design and evaluation; it does not demonstrate that a particular product produces spiritual growth.