"Ineffable" is a reasonable approximation for that. But, it
means that it cannot be spoken or described.
beyond words, celestial, divine, empyreal,empyrean, ethereal,
heavenly, holy, ideal,impossible, incommunicable,
incredible,indefinable, indescribable, inexpressible,nameless,
sacred, spiritual, too sacred for words,transcendent,
transcendental, unspeakable,untellable, unutterable