The idea that the “real” world we live in is not real is not a solely Christian idea. In Lewis’ books we come across the idea that, although this world is real, it is only a taste of a reality which is even MORE real (e.g. in his story “The Great Divorce”, in which everything in heaven is super-real.
Here, for comparison, are a few lines from the Hindu philosophical texts, the Upanishads:
“Lead me from the unreal to the real !
Lead me from darkness to light !
Lead me from death to immortality !”Brihad-aranyaka Upanishad, c. 800-400 BCE, 1.3.28