Religious and spiritual terminology constitutes one of the most semantically dense and culturally embedded domains in literary translation. When texts rooted in Christian and Islamic literary traditions cross linguistic boundaries, theological concepts, mystical vocabularies, and ritual lexicons encounter profound asymmetries in semantic range, doctrinal framing, and cultural resonance. This article presents a systematic contrastive analysis of religious-spiritual terminology in selected Christian and Islamic literary works, examining how translators negotiate theological precision, cultural alterity, and literary aesthetics. Drawing on a curated corpus of canonical and contemporary fiction, poetry, and devotional prose, the study maps key terminological fields (grace/rahma, spirit/ruh, sin/gunoh, divine light/nur, contemplation/muraqaba) and evaluates translation strategies through the lenses of functional equivalence, foreignization, and thick translation. Findings reveal that Christian literary terminology often operates within institutional-doctrinal frameworks, whereas Islamic literary vocabulary tends to emphasize relational, communal, and mystical dimensions. Translators frequently employ hybrid strategies, balancing theological fidelity with target-culture readability, though market-driven domestication risks semantic flattening. The article argues that religious translation in literature is not merely a linguistic transfer but a hermeneutic act of intercultural mediation. It offers methodological guidelines for translators, comparative scholars, and interfaith educators, while highlighting ethical imperatives in preserving theological alterity without exoticization.