Inference
Inference is based upon Established truth , towards Further truths.
Spiritual Inferencing only uses Spiritual intrinsic experience, perceived in one's spirit : the reason is because God is self-existent ( not dependent upon Physicality etc.) and Spirit of Truth ; thus Physicality is not required to know God.
Involution of God is possible by Himself alone, since He is Self-existent; He could/ has/ did manifest His energy in tangible and involute towards Perfection ( whole truth, love for all Sentience, no creation of any evil, only a purest intent )