Mystical experiences are purportedly a direct awareness of ultimate or transcendent reality, inaccessible through ordinary perception or rational inquiry. They are typically accompanied by a powerful sense of significance and reality (a "noetic quality"), leading experiencers to believe they have encountered what is fundamentally real. Empirical research shows that individuals who interpret such experiences as "encounters with God" sometimes shift from atheism to theism and often report greater well-being and life satisfaction. For epistemologists, a central question is whether a mystic is justified in treating their experience as a genuine source of knowledge or evidence about ultimate reality. Gellman's Argument from Perception holds that mystical experiences of God should be treated like ordinary perceptual experiences: just as perceiving a tree provides initially sufficient justification for believing it is present, so too does experiencing God justify belief in direct experiential contact with God. This argument presupposes a 'foundationalist' view of perceptual justification, according to which perceptual belief is justified by the experience alone, without requiring further confirming beliefs or evidence. A recent and increasingly influential development in cognitive science and philosophy of mind—the predictive processing (PP) theory—conceives of the brain as continuously generating and updating internal models to predict sensory input. Perceptual inferences are guided by how well new input coheres with the brain's existing model of the world, but are also constrained by sensory input. Since PP aligns with a 'foundherentist' account of perceptual justification, I explore whether Gellman's Argument from Perception can be reformulated in terms of such an account. If successful, such a reformulation could show that the Argument from Perception offers a persuasive account—especially for naturalists—for treating experiences of God as evidence for God's existence.