Oneness in Immortal true spirit that transcends time space barriers and mortality
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John 17:21 Bible NIV relevant portion only referred :
Oneness in Spirit of Truth renders Spiritual bonding , irrespective of physical & mortal barriers
( Public domain religious ref.)
Apparently, Jesus , in exalted Spirit state of being, also communicated with Prophets Moses and Elijah after the latter had passed away. ( Gospels)
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Whether through Realisation, continued unbroken Association with God (True eternal energy) , or through belief in Resurrection (victory over death in spirit, soul and body), the Oneness in Spirit of Truth (for those in Truth) exists.
"Similar Essences" have access to one another and are in Oneness in spiritual realm.
Real existence is Within, in Spiritual realm.
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No religious text is completely free of fault; if there is Scientific spiritual truth in it, it is acceptable.